Petite messe solennelle
... that Rossini scored the last of his "sins of old age", the Petite messe solennelle, for twelve singers, two pianos, and harmonium?
... that <a href="./Gioachino_Rossini" id="mwxQ" rel="mw:WikiLink" title="Gioachino Rossini">Rossini</a> <i id="mwxg">(pictured)</i> scored the last of his "sins of old age", the <i id="mwxw"><b id="mwyA"><a href="./Petite_messe_solennelle" id="mwyQ" rel="mw:WikiLink" title="Petite messe solennelle">Petite messe solennelle</a></b></i>, for twelve singers, two pianos, and <a href="./Pump_organ" id="mwyg" rel="mw:WikiLink" title="Pump organ">harmonium</a>?