This is the english translation I am reading from for Spinoza's Ethics Geometrically. In proposition IX of this work, spinoza states:
PROP. IX. The more reality or being a thing has, the greater the number of its attributes (Def. iv.)
Here, no proof is given (most of Spinoza's propositions are proven, but for simple ones at the beginning Spinoza merely cites the appropriate definitions and axioms). Hence, it appears that this proposition should follow from definition iv.
Now, definition iv states
By attribute, I mean that which the intellect perceives as constituting the essence of substance.
What I don't understand is how this definition informs us about the magnitude of the reality of a being thing. How does Spinoza's definition of an attribute render proposition ix a trivial consequence (as the mere citation as opposed to explicit proof seems to indicate)?