Non Dormit Qui Custodit

Here is today's emblem and distich by Gabriel Rollenhagen, Book 2:15, with an English rendering by George Wither.The crane was supposed to use a sly strategy for staying awake while on guard: the crane would hold up a rock with one leg so that, if the crane fell asleep, the rock hitting the ground would wake him up. The text of the poem reads sapori, but I have changed it to sopori. Can anybody think of a reason not to make this correction? Note also that the emblem contains the letters EPISCOP, from the Greek epi- (over) and -scop (look), which gives us the English word bishop.

Non Dormit Qui Custodit
Detinet hunc non alta quies similisque sopori,
Qui vigili, nostras res, ratione, regit.

A Shepherd carefull of the Sheepe
At all times, faithfull Watch doth keepe.

Here is the vocabulary:

non - no
dormio - sleep
qui - who, which, that
custodio - guard, stand guard
detineo - hold, keep, occupy
hic - this, this one
altus - high, talle, deep
quies - quiet, rest
similis - like, similar
que - and
sopor - deep sleep
vigil - awake, alert
noster - our, ours
res - thing
ratio - reckoning, plan, reasoning
rego - rule, guide, direct