Selection from – Ethics – Part II. On the Nature and Origin of the Mind (Page 1)
Spinoza's Words: (since (Deus sive Natura) is perfect the reality it produces is perfect)
As we should expect Spinoza begins Book II with definitions and axioms.
Definition III. By idea, I mean the mental conception which is formed by the mind as a thinking thing.
Explanation.—I say conception rather than perception, because the word perception seems to imply that the mind is passive in respect to the object; whereas conception seems to express an activity of the mind.
Definition VI. Reality and perfection I use as synonymous terms
I have selected these two definitions as most interesting. To Definition III Spinoza adds a short explanation because he wants us to know that he considers the mind an active thing that processes events not a mere spectator of them.
In Definition VI he reminds us that the products and processes of nature that we encounter in our daily lives are the way they are because of the unchangeable nature of physical laws. Wood is the way it is because the growth of a tree naturally produces plant cells whose walls contain cellulose and produce certain properties such as hardness, resistance to compression, and ability to burn. Wood is real and is perfect in its own way. If it was less than perfect, say that it could not burn, then it would not be wood.
Therefore reality = perfection, QED.
If men see imperfections it is because they lack understanding of Nature and would have things the way they want them to be.