I found this poem in the collection Philosophia Patrum edited by Julius Wegeler.
Si desit sapiens, sedes patet insipienti;
Tunc sedet insipiens, sed non similis sapienti.
The vocabulary is keyed to the DCC Latin Vocabulary list. There is only one word in this poem that is not on the DCC list:
insipiens, insipientis - foolish, without intelligence, unwise
dēsum -esse -fuī: be lacking
nōn: not
pateo -ēre patuī: lie open, extend, spread
sapiens -ntis: wise, sensible
sed: but
sedeo -ēre sēdī sessum: sit
sēdēs -is m.: seat, abode, habitation
sī: if
similis -e: like, similar
tum/tunc: then