Reason is the second kind of knowledge
Formal Statement
There are three kinds of knowledge: (1) imagination or opinion, from sensory experience and hearsay; (2) reason, from common notions and adequate ideas of properties; (3) intuition, from adequate ideas of God's attributes to the essence of things. Knowledge of the first kind is the only source of falsity; the second and third kinds are necessarily true.
In Plain Language
Spinoza now names the path out of confusion. Imagination — our default mode — delivers inadequate ideas and all the errors that come with them. Reason gives us common notions: universal truths that hold for all bodies and all minds. Intuition grasps singular essences directly. The key point is that there is a definite, nameable cognitive upgrade available: from confused sensory pictures to structural understanding. This is the lever that will pry us free of bondage.
Why This Follows
Steps 4-5 (df-04, df-05) showed that our default knowledge is inadequate but that adequate ideas are possible and self-certifying. This step identifies the cognitive faculty — reason — that reliably produces adequate ideas, giving us a concrete tool for the work ahead.
Reason is the named path from imagination's confusion to structural truth.
Connected Concepts
Think of something you once "just knew" from experience versus something you understand through its underlying principles. How does each kind of knowledge feel different in practice?