Full Idea
All things to be done or to be avoided pertain to the precepts of natural law, which practical reasoning apprehends naturally as being human goods.
Gist of Idea
Right and wrong actions pertain to natural law, as perceived by practical reason
Source
Thomas Aquinas (Summa Theologicae [1265], Ia IIae.Q94.2c), quoted by Kretzmann/Stump - Aquinas, Thomas 13
Book Reference
'Shorter Routledge Encyclopaedia of Philosophy', ed/tr. Craig,Edward [Routledge 2005], p.44
A Reaction
No mention of God, but you feel the divine presence in the background. He also cites 'eternal law'. No coincidence that the atheist Hobbes rejected natural law. Personally I would offer an atheistic defence of natural law, based on human nature.