"unitas diei accipitur secundum unitatem rei cognitae, quae tamen diversis cognitionibus cognosci potest."
Thomas Aquinas, Summa theologiae I.58.7.ad 1, trans. Ralph McInerny (Thomas Aquinas: selected writings, ed. & trans. Ralph McInerny (New York, NY: Penguin Books, 1998), 409).
The FEDP translation was much less pungent:
the day's unit is taken according to the unit of the thing understood; which, nevertheless, can be apprehended by various ways of knowing it.Aquinas refers here to the Augustinian distinction between the morning and the evening knowledge of the angels, i.e.
- their knowledge of things "per rationes rerum in verbo existentes" (by the rationes of things existing in the Word), and
- their knowledge of things "per species innatas" (by the species innate in and connatural to them, which species they receive from God, there being "likenesses of creatures in the mind of the angel, not as received from these creatures but rather from God, who is the cause of the creatures in whom the likenesses of things first exist" (I.55.2.ad 1 (380), italics mine)).