I found this poem in the collection Philosophia Patrum edited by Julius Wegeler.
Sic Vita Velut Umbra
Vita brevis, velut umbra levis, sic annihilatur;
Sic vadit subitoque cadit, dum stare putatur.
The vocabulary is keyed to the DCC Latin Vocabulary list. There are two words in this poem that are not on the DCC list:
annihilō, annihilāre: annihilate
vādo, vādere: go, walk, depart
brevis -e: short, shallow, brief; adv. breviter
dum: while (+ indic.); until (+ subj.); provided that (+ subj.)
levis -e: light, trivial
putō -āre: think, suppose
que (enclitic) - and
sīc: in this manner, thus; sīc . . . ut: in the same way as
stō stāre stetī statum: stand
subitō: suddenly, unexpectedly
umbra -ae f.: shade, shadow
velut: even as, just as
vīta -ae f.: life