This little poem comes from Disticha de Educatione of Urbano Appendini, published in 1834; you can see the whole book at Google Books.
Philosophus Naturalis
Felix cui nota est naturae causa latentis,
At sua qui noscat pectora, rarus adest.
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:
nātūrālis, -e (nātūrālis): natural, of nature
philosophus (philosophi, m.): philosopher
adsum adesse affuī: be present
at: but, but yet
causa -ae f.: cause, reason
fēlīx -īcis: lucky; adv. fēlīciter
lateō latēre latuī: lie hidden, be hidden
nātūra -ae f.: nature
nōscō nōscere nōvī nōtum: learn, know
nōtus -a -um: well-known
pectus -oris n.: chest, breast
qui quae quod: who, which, what / quis quid: who? what? which?
rarus -a -um: wide apart, loose, thin; rare, seldom
sum, esse, fuī: be, exist
suus -a -um: his own, her own, its own