Full Idea
Each indivisible substance contains in its nature the law by which the series of its operations continues, and all that has happened and will happen to it. All its actions come from its own depths, except for dependence on God.
Gist of Idea
A substance contains the laws of its operations, and its actions come from its own depth
Source
Gottfried Leibniz (Letters to Antoine Arnauld [1686], 1688.01.4/14)
Book Reference
Leibniz,Gottfried: 'The Leibniz-Arnauld Correspondence', ed/tr. Mason,HT/Parkinson,GHR [Manchester UP 1967], p.170
A Reaction
I take the combination of 'laws' and 'forces', which Leibniz attributes to Aristotelian essences, to be his distinctive contribution towards giving us an Aristotelian metaphysic which is suitable for modern science.