Full Idea
Hobbes' notion of 'conatus' is a 'beginning of motion' - a motion through a point of space in an instant of time. In a human subject this is experience as desire or aversion. It thus forms a bridge between physics and psychology.
Gist of Idea
A 'conatus' is an initial motion, experienced by us as desire or aversion
Source
report of Thomas Hobbes (De Corpore (Elements, First Section) [1655], p.178) by Richard T.W. Arthur - Leibniz 3 'Worlds'
Book Reference
Arthur, Richard T.W.: 'Leibniz' [Polity 2014], p.55
A Reaction
This sounds rather like the primitive concept of a power which I like, but the term seems to be used very vaguely, and never discussed carefully. The idea provoked Leibniz to connect physical force with mental life.