This is a distich from Daniël Heinsius' emblem collection entitled Ambacht van Cupido published in 1613. You can find the book online at the Emblem Project Utrecht.
Dissimulas frustra : quis enim celaverit ignem?
Lumen ab indicio proditur usque suo.
The vocabulary is keyed to the DCC Latin Vocabulary list. There are only three words in this poem that are not on the DCC list:
cēlō, -āre - hide, conceal, keep secret
dissimulō, -āre - dissemble, disguise, keep secret
indicium, indiciī n. - evidence, sign, proof
ā ab abs: from, by (+abl.)
enim: for, indeed
frūstrā: in vain
īgnis -is m.: fire
lūmen luminis n.: light
prodō prodere prodidī proditum: publish, hand down; give over, betray
qui quae quod: who, which, what / quis quid: who? what? which?
suus -a -um: his own, her own, its own
ūsque: up to; continuously