Cartier-Bresson's l'instant décisif: photography is the simultaneous recognition of the significance of an event and the precise organization of forms that give it proper expression.
The phrase is often misread as "act fast, shoot instinctively." What Cartier-Bresson meant was closer to: you must understand geometry well enough that when the moment arrives, you already know where to be standing.
Preparation + patience + geometry. The decisive moment is the outcome of everything that came before it.
See: ↗ @carol / practice-vs-playing — the same structure: visible preparation, invisible technique.