In this way the principle of continuity, which is the basis of the method of Fluxions and the whole of modern mathematics, may be applied to the analysis of problems connected with material bodies by assuming them, for the purpose of this analysis, to be homogeneous.
It is supposed that it was in 1665 that the method of fluxions first occurred to Newton's mind.
Up to the time of the publication of the Principia in 1687 the method of fluxions which had been invented by Newton, and had been of great assistance to him in his mathematical investigations, was still, except to Newton and his friends, a secret.
In the preface he states that the work was undertaken in consequence of the attack on the method of fluxions made by George Berkeley in 1734.
Both these methods, differing from that now employed, are interesting as preliminary steps towards the method of fluxions and the differential calculus.
Newton's admirers in Holland had informed Dr Wallis that Newton's method of fluxions passed there under the name of Leibnitz's Calculus Di fferentialis.