Take it home, put it in your CD player, and concentrate on the music, the chords, the flow, the buildup of forty different voices singing forty different parts, all coalescing into an unbelievably cohesive vocal masterpiece. You will not be disappointed.
It’s even better when you can follow the words:
Spem in alium, nunquam habui prater in te, Deus Israel, qui irasceris, et propitius eris, et omnia peccata hominum in tribulatione dimittis. Domine Deus, Creator coeli et terrae, respice humilitatem nostram.
The text is from the History of Judith (an apocryphal book, I think), and is roughly translated, “I hope only in you and no other, God of Israel, who angers, is again gracious, and forgives all man’s sins in his suffering. Lord God, Creator of Heaven and Earth, see our disgrace/humility.”
Tallis saw interesting days in English history, serving through the reigns of Henry VIII, Edward VI, “Bloody” Mary Tudor, and Elizabeth I — and adapting his music for the religious environment of each reign. It was probably during the latitudinarian days of Elizabeth that he wrote the 40-Part motet.
Interestingly enough, I also have a recording of the Kyrie from Antoine Brumel’s Missa “Et ecce terrae motus, and it strikes me how similar they sound. Well, okay, not too similar. Few compositions can approach the historic grandeur of Spem in Alium, but the same “cosmic” atmosphere permeates Brumel just as it does Tallis. They obviously had a rich weave of tradition to draw from that period.