An objection asks: if essence and attribute are not “other,” why can we consider them separately? The reply distinguishes two senses of conceiving something: isolating a meaning as a topic of thought, and asserting the actual possibility of its independent existence.
One may focus intellectually on the concept of essence without showing that God could exist without knowledge or power. Equally, discussing knowledge in isolation does not prove that it exists independently of God.
Abstraction in thought must be distinguished from real separation. Otherwise every analytically distinguishable meaning would be turned into a separate external entity.