Sicut Cervus is a setting of Psalm 42:1 (Vulgate version). As noted above, it is a motet composed by Giovanni Pierluigi da Palestrina. Like many of Palestrina's works, it utilizes imitative polyphony.

The original Latin text is as follows (with a * denoting the beginning of each imitated 'movement' of the piece):

*Sicut cervus desiderat ad fontes aquarum,
*Ita desiderat *anima mea ad te, Deus.
Translated into English, it equates roughly to "Like as the hart desireth the water brooks, so longeth my soul after thee, O God".

I extend my thanks to the mysterious noders who subtly added to and corrected bits of (well, one typo) my writeup via softlinks.