Spem in alium, nunquam habui

Praeter in te, Deus Israel

Qui irasceris et propitius eris

et omnia peccata hominum

in tribulatione dimitis

Domine Deus

Creator caeli et terrae

respice humilitatem nostram

So Tallis was already established as one of the best composers in the known world (in Tudor England) when he wrote this short choral work (about 10 minutes long).  He wrote it for an unprecedented 8 choirs singing at the same time, each with 5 vocal parts (Treble, alto, tenor, baritone, bass) hence “motet for 40 voices”.  Part of the attraction (and difficulty) is the three dimensional quality of the music, different choirs singing at the same time, possibly not even able to see each other.
The humble words stand rather at odds with the achievement of the piece.