It gave us both quite a Santa Claus feeling on Xmas Eve to see him so excited and hopeful; I enjoyed it hugely.
— from The Letters of Robert Louis Stevenson — Volume 1 by Robert Louis Stevenson

No method can justly be regarded as bearing any analogy to the differential calculus which does not lay down a system of rules (no matter on what considerations founded, by what names called, or by what extraneous matter enveloped) by means of which the second term of the development of any function of x + e in powers of e , can be correctly calculated, ‘quæ extendet se,’ to use Newton’s expression, 172 ‘ citra ullum molestum calculum in terminis surdis æque ac in integris procedens .’
— from The Life of Sir Isaac Newton by David Brewster

It gave us both quite a Santa Claus feeling on Xmas Eve to see him so excited and hopeful; I enjoyed it hugely.—Your affectionate son, Robert Louis Stevenson.
— from The Works of Robert Louis Stevenson - Swanston Edition, Vol. 23 by Robert Louis Stevenson

Each of the four co-ordinates x', e', x', y' are functions of x, e, x, y; and if it be assumed that the field of view and the aperture be infinitely small, then x, e, x, y are of the same order of infinitesimals; consequently by expanding x', e', x', y' in ascending powers of x, e, x, y, series are obtained in which it is only necessary to consider the lowest powers.
— from The Project Gutenberg Encyclopedia Volume 1 of 28 by Project Gutenberg