Moteur de template Twig

Bonjour,
Je suis en train de tester le moteur de template Twig.
Dans mon application, j'ai une classe Month comme suit :

<?php 

namespace Calendrier;

class Month extends Date
{
   public $year;
   public $month;
   public $holidays  = [];
   public $feries    = [];
   public $cathol    = [];
   public $catho     = [];
   public function __construct(?int $year = null)
   {
      if ($year === null) {
         $year = intval(date('Y'));
      }
      $this->year = $year;
   }
   public function previousYear()
   {
      $year = $this->year - 1;

      return $year;
   }
   public function nextYear()
   {
      $year = $this->year + 1;

      return $year;
   }
   /**
    * Retourne le tableau des libellés jours fériés
    *
    * @return array
    */
   public function getHolidays() : array
   {
      $holidays = [
         "Jour de l'an",
         "Lundi de pâques",
         "Lundi de pentecôte",
         "Ascension",
         "Fête du travail",
         "Victoire des alliés",
         "Fête nationale",
         "Assomption",
         "Toussaint",
         "Armistice 1918",
         "Noël",
      ];

      $this->holidays = $holidays;

      return $this->holidays;
   }
   /**
    * Retourne le tableau des jours fériés
    *
    * @return array
    */
   public function getFeries() : array
   {
      $feries[] = $this->year . '0101';                          // Jour de l'an
      $feries[] = $this->lundiPaques($this->year);               // Lundi de pâques
      $feries[] = $this->lundiPentecote($this->year);            // Lundi de pentecôte
      $feries[] = $this->ascension($this->year);                 // Ascension
      $feries[] = $this->year . '0501';                          // Fête du travail
      $feries[] = $this->year . '0508';                          // Victoire des alliés
      $feries[] = $this->year . '0714';                          // Fête nationale
      $feries[] = $this->year . '0815';                          // Assomption
      $feries[] = $this->year . '1101';                          // Toussaint
      $feries[] = $this->year . '1111';                          // Armistice 1918
      $feries[] = $this->year . '1225';                          // Noël

      $this->feries = $feries;

      return $this->feries;
   }
   /**
    * Retourne le noùbre de postes du tableau feries
    *
    * @return integer
    */
   public function countFeries() : int
   {
      return $count = count($this->feries);
   }
   /**
    * Retourne le tableau des jours des fêtes catholiques
    *
    * @return array
    */
   public function getCathol() : array
   {
      $cathol = [
         "Épiphanie",
         "Chandeleur",
         "Mardi gras",
         "Cendres",
         "Annonciation",
         "Rameaux",
         "Jeudi saint",
         "Vendredi saint",
         "Pâques",
         "Pentecôte",
         "Fête des morts"
      ];

      $this->cathol = $cathol;

      return $this->cathol;
   }
   /**
    * Retourne le tableau des fêtes catholiques
    *
    * @return array
    */
   public function getCatho() : array
   {
      $catho[] = $this->epiphanie($this->year);                // Épihanie
      $catho[] = $this->chandeleur($this->year);               // Chandeleur
      $catho[] = $this->mardiGras($this->year);                // Mardi gras
      $catho[] = $this->cendres($this->year);                  // Mercredi des cendres
      $catho[] = $this->annonciation($this->year);             // Annonciation à la vierge
      $catho[] = $this->rameaux($this->year);                  // Dimanche des rameaux
      $catho[] = $this->jeudiSaint($this->year);               // Jeudi saint
      $catho[] = $this->vendrediSaint($this->year);            // Vendredi saint
      $catho[] = $this->paques($this->year);                   // Pâques
      $catho[] = $this->pentecote($this->year);                // Pentecôte
      $catho[] = $this->year . '1102';                         // Fête des morts

      $this->catho = $catho;

      return $this->catho;
   }
   /**
    * Retoune le nombre de postes du tableau catho
    *
    * @return integer
    */
   public function countCatho() : int
   {
      return $count = count($this->catho);
   }
   /**
    * Retourne le libellé du mois
    *
    * @param Int $index
    * @return string
    */
   public function rtvMonthName(Int $index) : string
   {
      return $this->months[$index];
   }
   /**
    * Retourne le nombre de jours dans le mois
    *
    * @param Int $index
    * @return integer
    */
   public function getNumDays(Int $index) : int
   {
      return $index == 2 ? ($this->year % 4 ? 28 : ($this->year % 100 ? 29 : ($this->year % 400 ? 28 : 28))) : (($index - 1) % 7 % 2 ? 30 : 31);
   }
   /**
    * Affiche le premier semestre
    *
    * @return void
    */
   public function getFirstSemDays() 
   {
      $year   = $this->year;
      $toDay  = date('Ymd');
      $result = '';
      for ($mo = 1; $mo <= 1 ; $mo++) {
         $result .= '<div class="month">';
         $result .= '<div class="month__head">';
         $result .= '<i class="fa fa-calendar"></i>';
         $result .= '<span class="month__head-month">';
         $result .= $this->rtvMonthName($mo);
         $result .= '</span>';
         $result .= '<span class="month__head-day">jour</span>';
         $result .= '<span class="month__head-sem">sem</span>';
         $result .= '</div><!-- /.month__head-->';
         for ($i = 1; $i <= $this->getNumDays($mo); $i++) { 
            $x    = ($i < 10 ? '0'    : '') . $i;
            $mois = ($mo < 10 ? '0': '') . $mo;
            $date = $year . $mois . $x;
            $j    = date('j', strtotime($date));
            $n    = date('N', strtotime($date));
            $w    = intval(date('W', strtotime($date)));
            $doy  = intval(strftime("%j", strtotime($date)));
            $day  = $this->days[$n];
            
            if (in_array($date, $this->getFeries())) {
               $result .= '<div class="days green">';
            } elseif ($date == $toDay) {
               $result .= '<div class="days yellow">';
            } else {
               $result .= '<div class="days">';
            }
            $result .= '<span class="day">' . $day . '</span>';
            $result .= '<span class="nday">' . $j . '</span>';
            $result .= '<span class="jour">' . $doy . '</span>';
            $result .= '<span class="sem">' . $w . '</span>';
            $result .= '</div><!-- /.days -->';         
         }
         $result .= '</div><!-- /.month -->';

         echo $result;
      }
   }
   /**
    * Affiche le deuxième semestre
    *
    * @return void
    */
   public function getSecondSemDays()
   {
      $year = $this->year;
      $toDay = date('Ymd');
      for ($mo = 7; $mo <= 12; $mo++) {
         $result = '';
         $result .= '<div class="month">';
         $result .= '<div class="month__head">';
         $result .= '<i class="fa fa-calendar"></i>';
         $result .= '<span class="month__head-month">';
         $result .= $this->rtvMonthName($mo);
         $result .= '</span>';
         $result .= '<span class="month__head-day">jour</span>';
         $result .= '<span class="month__head-sem">sem</span>';
         $result .= '</div><!-- /.month__head-->';
         for ($i = 1; $i <= $this->getNumDays($mo); $i++) {
            $x = ($i < 10 ? '0' : '') . $i;
            $mois = ($mo < 10 ? '0' : '') . $mo;
            $date = $year . $mois . $x;
            $j = date('j', strtotime($date));
            $n = date('N', strtotime($date));
            $w = intval(date('W', strtotime($date)));
            $doy = intval(strftime("%j", strtotime($date)));
            $day = $this->days[$n];

            if (in_array($date, $this->getFeries())) {
               $result .= '<div class="days green">';
            } elseif ($date == $toDay) {
               $result .= '<div class="days yellow">';
            } else {
               $result .= '<div class="days">';
            }
            $result .= '<span class="day">' . $day . '</span>';
            $result .= '<span class="nday">' . $j . '</span>';
            $result .= '<span class="jour">' . $doy . '</span>';
            $result .= '<span class="sem">' . $w . '</span>';
            $result .= '</div><!-- /.days -->';
         }
         $result .= '</div><!-- /.month -->';

         echo $result;
      }
   }
   public function dspFeries()
   {
      $array1 = $this->getHolidays();
      $array2 = $this->getFeries();
      array_multisort($array2, $array1);
      // Formattage de l'affichage
      for ($i = 0; $i < $this->countFeries(); $i ++) { 
         $result = '<div class="feries__libday">';
         $result .= '<div class="feries__libday-day">';
         $result .= $array1[$i];
         $result .= '</div><!-- /.feries__libday-day -->';
         $result .= '<div class="feries__libday-jour">';
         $result .= $this->rtvWeekDay($array2[$i]);
         $result .= '</div><!-- /.feries__libday-jour -->';
         $result .= '<div class="feries__libday-numday">';
         $result .= $this->rtvDay($array2[$i]);
         $result .= '</div><!-- /.feries__libday-numday -->';
         $result .= '<div class="feries__libday-month">';
         $result .= $this->rtvMonth($array2[$i]);
         $result .= '</div><!-- /.feries__libday-month -->';
         $result .= '</div><!-- /.feries__libday -->';

         echo $result;
      }
   }
   public function dspCatho()
   {
      $array1 = $this->getCathol();
      $array2 = $this->getCatho();
      $count  = count($array2);
      array_multisort($array2, $array1);
      // Formattage de l'affichage
      for ($i = 0; $i < $this->countCatho(); $i++) {
         $result = '<div class="catho__libday">';
         $result .= '<div class="catho__libday-day">';
         $result .= $array1[$i];
         $result .= '</div><!-- /.catho__libday-day -->';
         $result .= '<div class="catho__libday-jour">';
         $result .= $this->rtvWeekDay($array2[$i]);
         $result .= '</div><!-- /.catho__libday-jour -->';
         $result .= '<div class="catho__libday-numday">';
         $result .= $this->rtvDay($array2[$i]);
         $result .= '</div><!-- /.catho__libday-numday -->';
         $result .= '<div class="catho__libday-month">';
         $result .= $this->rtvMonth($array2[$i]);
         $result .= '</div><!-- /.catho__libday-month -->';
         $result .= '</div><!-- /.catho__libday -->';

         echo $result;
      }
   } 
}

Je veux afficher le premier semestre dans home.twig, j'essaye de le faire comme cela :
1- fichier index.php

<?php 
// Autoloading
require './src/bootstrap.php';


// Initialisations
// Dates
$date  = new Calendrier\Date();
$today = $date->getDate();
$sem   = $date->getWeek();
$day   = $date->getDayNum();
$reste = $date->reste();


// Mois
$month     = new Calendrier\Month($_GET['year'] ?? null);
$year      = $_GET['year'] ?? date('Y');
$dref      = $year . '0630';

//$semestre1 = $month->getFirstSemDays();

//$sem2    = $month->getSecondSemDays();

$previous  = $month->previousYear();
$next      = $month->nextYear();

$title     = 'Calendrier';
$titre     = $title . ' ' . $year;

// URL
$host = $_SERVER['HTTP_HOST'];
$uri = $_SERVER['REQUEST_URI'];
$url = sprintf("%s%s%s", "http://", $host, $uri);
$http = explode('/', $url);
$url = $http[0] . '//' . $http[2] . '/' . $http[3];

// Routing
$page = 'home';
if (isset($_GET['p'])) {
   $page = $_GET['p'];
}

// Rendu du template
$loader = new Twig_Loader_Filesystem(__DIR__ . '/templates');
$twig   = new Twig_Environment($loader, [
   'cache' => false //__DIR__ . '/tmp'
]);

if ($page === 'home') {
   echo $twig->render('home.twig', [
      'date'     => $today,
      'sem'      => '(Semaine: ' . $sem . ')',
      'day'      => ' (Jour : ' . $day . ')',
      'reste'    => ' (' . $reste . ')',
      'titre'    => $titre,
      'title'    => $title,
      'url'      => $url,
      'previous' => $previous,
      'next'     => $next,
      'month'    => $month->getFirstSemDays()
   ]);
}

2-Fichier home.twig :

{% extends 'layout.twig' %}

{% block head %}
   <title>{{ title }}</title>
{% endblock %}

{% block content%}
   <div class="container">
      <header class="header">
      <div class="header__top">
         <div class="header__top-date">
         {{ date }} <br>
         {{ sem ~ day ~ reste }}
         </div><!-- /.header__top-date -->
         <div class="header__top-titre text-center">
            <a href="/"><i class="fa fa-calendar"></i> {{ titre }} </a>
         </div><!-- /.header__top-titre -->
         <div class="header__top-time">
            <i class="fa fa-clock-o"></i> <span id="time"><script>window.onload=dspTime('time')</script></span>
         </div><!-- /.header__top-time -->
      </div><!-- /.header__top -->
      </header><!-- /header -->
      <nav class="nav">
         <div class="previous__year">
            <a href="{{ url }}/?year={{ previous }}"><Précédent></a>
         </div><!-- /.previous__year -->
         <ul class="menu">
            <li class="active"><a href="#sem1" id="sema">Semestre 1</a></li>
            <li><a href="#sem2" id="semb">Semestre 2</a></li>
            <li><a href="#feries" id="fera">Jours fériés</a></li>
         </ul><!-- /.menu -->
         <div class="next__year">
            <a href="{{ url }}/?year={{ next }}"><Suivant></a>
         </div><!-- /.previous__year -->
      </nav><!-- /.nav -->
    <section id="sem1" class="section">
     <h1 class="text-center">Premier Semestre</h1>
     <hr class="hr">
     <div class="mois">
       {{ month }}
     </div><!-- /.mois -->
   </section><!-- /#sem1 /.section -->
   <section id="sem2" class="section">
     <h1 class="text-center">Deuxième Semestre</h1>
     <hr class="hr">
     <div class="mois">

     </div><!-- /.mois -->
   </section><!-- /#sem1 /.section -->
{% endblock %}
{% block foot %}
        <footer class="footer text-center">
          <p>© Copyright. <a href="{{ url }}">{{ title }} {{ "now" | date('Y') }}</a>. Tous Droits Réservés.</p>
        </footer><!-- /footer -->
      </div><!-- /.container -->
      <!-- Scripts -->
      <script src="js/jquery-3.2.1.min.js"></script>
      <script src="js/calend.js"></script>
   </body>
</html>
{% endblock %} 

Le résultat est qu'il affiche le premier semestre à gauche de la page alors qu'il devrait me le mettre entre
la balise

<div class="mois">
   {{ month }}
</div><!-- /. mois --> 

Merci de votre aide.
Cordialement