Full Idea
The force by which a man perserveres in existing is limited, and infinitely surpassed by the power of external causes.
Gist of Idea
Our own force of persevering is nothing in comparison with external forces
Source
Baruch de Spinoza (The Ethics [1675], IV Pr 03)
Book Reference
Spinoza,Benedict de: 'Ethics', ed/tr. Curley,Edwin [Penguin 1996], p.118
A Reaction
This states the obvious, but is important as a way of viewing things. I think Nietzsche's notion of Will to Power comes in here, as a unified account of both forces.