Full Idea
The effort by which each thing endeavours to persevere in its own being is nothing but the actual essence of the thing itself.
Gist of Idea
The essence of a thing is its effort to persevere
Source
Baruch de Spinoza (The Ethics [1675], III Pr 07)
Book Reference
Spinoza,Benedict de: 'Ethics', ed/tr. White,WH/Stirling,AH [Wordsworth 2001], p.105
A Reaction
This is exactly the sort of thing that Leibniz frequently said. They were much more conscious of the active power of essences than in the scholastic tradition. This is Nietzsche's will to power. Spinoza talks of 'power' in his demonstration of this.
Related Idea
Idea 7142 All motions and 'laws' are symptoms of inner events, traceable to the will to power [Nietzsche]