Time is the indefinite continued progress of existence and events that occur in apparently irreversible succession from the past through the present to the future. Time is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, and to quantify rates of change of quantities in material reality or in the conscious experience. Time is often referred to as a fourth dimension, along with three spatial dimensions.
Minutes, hours, days, months, and years, Pass'd over to the end they were created, Would bring white hairs unto a quiet grave. Ah, what a life were this!
William Shakespeare, Henry VI, Part III (c. 1591), Act II, scene 5, line 35
I consider time as flowing or increasing by continual flux & other quantities as increasing continually in time & from ye fluxion of time I give the name of fluxions to the velocitys wth wch all other quantities increase. ...I expose time by any quantity flowing uniformly and represent its fluxion by an unit, & the fluxions of other quantities I represent by any other fit symbols... This Method is derived immediately from Nature her self.
Isaac Newton, draft review of Commercium epistolicum (1712) The Mathematical Papers of Isaac Newton (1969) Vol. 3, ed. D. T. Whiteside, p. 17.
