"It appears then that the distance between one thing and another does not depend on any material thing between them, a…"

"What I have given in the second book on the nature and properties of curved lines, and the method of examining them, …"

"No more useful inquiry can be proposed than that which seeks to determine the nature and the scope of human knowledge…"

"Mr. Clerselier has written me that you are expecting from him my Meditations... in order to present them to the queen…"

"Mais apud me omnia fiunt Mathematicè in Natura"

"No doubt you know that Galileo had been convicted not long ago by the Inquisition, and that his opinion on the moveme…"

"M. Desargues puts me under obligations on account of the pains that it has pleased him to have in me, in that he show…"

"Je pense, donc je suis."

"Le bon sens est la chose du monde la mieux partagée : car chacun pense en être si bien pourvu, que ceux même qui sont…"

"Me tenant comme je suis, un pied dans un pays et l'autre en un autre, je trouve ma condition très heureuse, en ce qu'…"