The natural law is nothing other than the light of understanding placed in us by God; through it we know what we must do and what we must avoid. God has given this light or law at the creation. 8
Catechism number 1958
The natural law is immutable and permanent throughout the variations of history;10 it subsists under the flux of ideas and customs and supports their progress. the rules that express it remain substantially valid. Even when it is rejected in its very principles, it cannot be destroyed or removed from the heart of man. It always rises again in the life of individuals and societies: