Page:Life of Sir William Petty 1623 – 1687.djvu/29

 Kepler, and Hervey. Hobbes himself was the rival and rather petulant correspondent of Descartes on the origin of knowledge.

The following letters written at this time by William Petty to Dr. Pell, who had fled to Amsterdam owing to the stress of the times, may be read with interest. Pell is now chiefly remembered for his controversy with the Danish mathematician, Longomontanus, on the quadrature of the circle, a subject which had also a fatal attraction for Hobbes: —

'Sir,—Father Mersen, his desire to convey this inclosed to you, serves me for a happie occasion to express my thankfulness for ye good of that acquaintance with Mr. Hobbes, which your letters procured mee; for by his meanes, my Lord of Newcastle, and your good friend, Sir Charles Cavendish, have been pleased to take notice of mee; and by his meanes also, I became acquainted with Father Mersen, a man who seems to mee not in any meane degree to esteem you and your works; and who wishes your studies may ever succeede happily, hoping (as others doe) that ye world shall receyve hope and benefitt by them. Sir, I desire you not to conceive that any neglect or forgetfulness hath caused my long silence, for ye often speech I have of you, either with Sir Charles, Mr. Hobbes, and Father Mersen (besides the courtesy I receyved from you), makes mee sufficiently to remember you. But to speake ye truth, it was want of business worthy to make ye subject of a letter of 16d postage, especially since Mr. Hobbes served you in procuring and sending you ye demonstrations of our French mathematicians. I could wish, with Sir Charles, that we could see your way of Analyticks abroad; or, if a systeme of ye whole Art were too much to hope for, for my owne part I could wish wee had your "Deophantus," which was ready for ye press before my departure from you. Those rules of Algebra (though few) which you gave me, and exercise, have made mee able to doe many pretty questions. I entend to reade no Author of that