This article traces the lived occurrence of a spontaneous, improvisatory event. Using choreographer Jeanine Durning’s performance ofingingas both a touchstone and a springboard, the affects of spontaneity are transversally mapped through a variety of generative operations. This diagrammatic approach reveals a topology of entangled concepts that convolve to abiogrammatichypothesis on thein situfielding of composition. Concepts such as the quasi-cause, counter-actualization, the concresence of prehensions, middling, stuttering, thermodynamic entropy, proprioception, far from equilibrium states, risk-taking, and machinic autopoiesis are folded into a speculative proposition on the forces that potentially excite an affective event through the practice of improvisational composing.