After having foretold the moment of his death, he fell asleep in the Lord in 1142, and in heaven his brow was encircled with "the crown of precious stones" (Gradual, Offertory), the symbol of his virtues.
Let us walk in the footsteps of St. William, with the help of his prayers (Collect).
Os justi meditabitur sapientiam, et lingua ejus loquetur judicium; lex Dei ejus in corde ipsius. * Noli aemulari in malignantibus: neque zelaveris facientes iniquitatem.
The mouth of the just shall meditate wisdom, and his tongue shall speak judgement: the law of his God is in his heart. * Be not emulous of evildoers: nor envy them that work iniquity.
(Psalm 36:30-31,1 from the Introit of Mass)
Deus, qui infirmitati nostrae, ad terendam salutis viam in Sanctis tuis exemplum et praesidium collocasti: da nobis, ita beati Gulielmi Abbatis merita venerari: ut ejusdem excipiamus suffragia, et vestigia prosequamur.
O God, who, to help our weakness, hast given us Thy saints to be our example and protection in the way of salvation; grant that we may so venerate the merits of the blessed abbot, William, that we may both gain his prayers and follow in his footsteps.
From the Catholic Encyclopaedia: http://www.newadvent.org/cathen/15639b.htm