Roughly put, we are the complete causes of our actions but only partial causes of our passions. Spinoza recognizes three primary affects. The affect of joy occurs when the mind passes to a greater perfection and the affect of sadness occurs when the mind passes to a lesser perfection. Because of the identity that there is between mind and body, the mind passes to a greater perfection just in case the body's power of acting is increased and the mind passes to a lesser perfection when the body's power of acting is diminished. In saying that joy, sadness, and desire are three primitive affects Spinoza means that all other affects can be defined with their help.
Love is a joy, accompanied by the idea of an external cause.
Hate is a sadness, accompanied by the idea of an external cause. Affects are further divided into actions and passions. Those affects whose adequate cause we are are active affects whereas those whose partial cause are passive affects. Because active affects bring always joy with them they can never be bad. Passive affects bring either sadness or joy with them.