Thus, observing that the bare rubbing of two bodies violently one upon another, produces heat, and very often fire itself, we have reason to think, that what we call HEAT and FIRE consists in a violent agitation of the imperceptible minute parts of the burning matter.
Horrela, bi gorputzen arteko igurtzi soil bortitzak beroa, eta sarritan sua ere, sortarazten duela hautematen dugunez, guk beroa eta sua deitzen diogun hori materia goriaren ataltxo ikustezinen eraginaldia dela pentsatzeko motiboak ditugu.