Metrum 4:P. asserts the powers of the mind against Stoic doctrines of the mind as tabula rasa . Meter: Glyconic.
Porticus: "The Porch," i.e., the Stoa of Athens, where under Zeno was born the Stoicism that is attacked in these lines.
corporibus: second syllable scanned long here. extimis: "outermost," i.e., alien from the spirit within.
ut: "just as." quondam: "sometimes."
The image is from the stylus-marked wax tablet, the everyday writing material of antiquity. aequore: any smooth, level surface; ablative of place where with figere (line 9).
propriis . . . motibus: "by its own activity."
notis: here, the impressions made on the senses.
cassas: "empty, insubstantial." in speculi vicem: "in the manner of a mirror."
singula . . . cognita . . . divisa: accusative plural.
Compare the description of P. in 1P1.2.
sese referens sibi: "bringing itself back to itself," after considering all things lofty and deep.
efficiens . . . causa: technical term of logic: "efficient cause." efficiens magis = efficientior .
longe: with potentior , for emphasis.
quae: sc. causa . materiae modo: "in the manner of matter."
passio: "suffering, experience" (cf. patitur ); some bodily experience (at least sensory impression) precedes mental activity.
species: object of both vocans and applicat , attracted into the relative clause.
notis . . . exteris: " notae [coming from] outside."
introrsum: adverb with reconditis .