Full Idea
I maintain that substances (material or immaterial) cannot be conceived in their bare essence devoid of activity; that activity is of the essence of substance in general
Gist of Idea
Substances cannot be bare, but have activity as their essence
Source
Gottfried Leibniz (New Essays on Human Understanding [1704], Pref 65)
Book Reference
Leibniz,Gottfried: 'New Essays on Human Understanding', ed/tr. Remnant/Bennett [CUP 1996], p.65
A Reaction
Leibniz liked the idea that God was the source of this activity, but this remark makes Leibniz a direct ancestor of modern scientific essentialism.