This is a poem by John Dunbar (c. 1585 - 1626), a Scottish neo-Latin poet. You can read more about Dunbar at Dana Sutton's online edition of Dunbar's epigrammatic poetry.
Nec lege quae iubeo, nec quae te iusserit alter,
Sed lege quae genio sunt mage grata tuo.
The vocabulary is keyed to the DCC Latin Vocabulary list. There are two words in this poem that are not on the DCC list:
genius (geniī, m.): tutelar deity, spirit
lector (lectōris, m.): reader
ad: to, up to, towards (+acc.)
alter altera alterum: other of two
grātus -a -um: pleasant; grateful
iubeō iubēre iūssī iūssum: bid, order
legō legere lēgī lēctum: gather, choose, read
neque nec: and not, nor; neque . . . neque, neither . . . nor
qui quae quod: who, which, what / quis quid: who? what? which?
sum, esse, fuī: be, exist
tū tuī tibi tē: you (sing.)
tuus -a -um: your