Full Idea
There is a fundamental axiom that 'nothing happens without reason', without which the existence of God and other great truths cannot be properly demonstrated.
Gist of Idea
Without the principle of sufficient reason, God's existence could not be demonstrated
Source
Gottfried Leibniz (New Essays on Human Understanding [1704], 2.21.13)
Book Reference
Leibniz,Gottfried: 'New Essays on Human Understanding', ed/tr. Remnant/Bennett [CUP 1996], p.179
A Reaction
I'm rather drawn to the Principle of Sufficient Reason, but also to John Keats's 'negative capability'. Belief that there must be a reason in each case is not a justification for inventing a reason every time. There may be a reason for the universe....