“In my Judgment no Lines ought to be admitted into plain Geometry besides the right Line and the Circle.”
p, 125
Arithmetica Universalis (1707)
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Isaac Newton 171
British physicist and mathematician and founder of modern c… 1643–1727Related quotes

The geometry of the spherical surface can be viewed as the realization of a two-dimensional non-Euclidean geometry: the denial of the axiom of the parallels singles out that generalization of geometry which occurs in the transition from the plane to the curve surface.
The Philosophy of Space and Time (1928, tr. 1957)

“I did my best to go in a circle, hoping in this way to go in a straight line.”
Molloy (1951)
Context: Having heard, or more probably read somewhere, in the days when I thought I would be well advised to educate myself, or amuse myself, or stupefy myself, or kill time, that when a man in a forest thinks he is going forward in a straight line, in reality he is going in a circle, I did my best to go in a circle, hoping in this way to go in a straight line. For I stopped being half-witted and became sly, whenever I took the trouble … and if I did not go in a rigorously straight line, with my system of going in a circle, at least I did not go in a circle, and that was something.

“A circle is a round straight line with a hole in the middle.”
Quoting a schoolchild in "English as She Is Taught"
Source: Mathematical Thought from Ancient to Modern Times (1972), p. 454

Arithmetica Universalis (1707)
Context: Geometry was invented that we might expeditiously avoid, by drawing Lines, the Tediousness of Computation. Therefore these two Sciences ought not to be confounded. The Antients did so industriously distinguish them from one another, that they never introduc'd Arithmetical Terms into Geometry. And the Moderns, by confounding both, have lost the Simplicity in which all the Elegancy of Geometry consists. Wherefore that is Arithmetically more simple which is determin'd by the more simple Æquations, but that is Geometrically more simple which is determin'd by the more simple drawing of Lines; and in Geometry, that ought to be reckon'd best which is Geometrically most simple. Wherefore, I ought not to be blamed, if with that Prince of Mathematicians, Archimedes and other Antients, I make use of the Conchoid for the Construction of solid Problems.<!--p.230

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The Differential and Integral Calculus (1836)
Geometry as a Branch of Physics (1949)