Full Idea
The counterpart of understanding God as identical with Nature is understanding ethics as the study not of divine precepts but of our own nature and of what necessarily moves us.
Gist of Idea
Along with his pantheism, Spinoza equates ethics with the study of human nature
Source
report of Baruch de Spinoza (The Ethics [1675]) by Alasdair MacIntyre - A Short History of Ethics Ch.10
Book Reference
MacIntyre,Alasdair: 'A Short History of Ethics' [Routledge 1967], p.142
A Reaction
As stated here, this seems wrong. We should approach ethics through Aristotle, but not through Freud. That is, virtues can be inferred from human nature, but the actual facts of human nature may be grubby and unpalatable.