Irritating as it was, it did not avail to shake Hobbes's determination to remain silent; and thus at last there was peace for a time. Before the strife flamed up again, Hobbes had published, in 1658, the outstanding section of his philosophical system, and thus completed, after a fashion, the scheme he had planned more than twenty years before. So far as the treatise _De homine_ (_L.W._ ii. 11-32) was concerned, the completion was more in name than in fact. It consisted for the most part of an elaborate theory of vision which, though very creditable to Hobbes's scientific insight, was out of place, or at least out of proportion, in a philosophical consideration of human nature generally. The remainder of the treatise, dealing cursorily with some of the topics more fully treated in the _Human Nature_ and the _Leviathan_, has all the appearance of having been tagged in haste to the optical chapters (composed years before)[15] as a makeshift for the proper transition required in the system from questions of Body Natural to questions of Body Politic. Hobbes had in fact spent himself in his earlier constructive efforts, and at the age of seventy, having nothing to add to his doctrine of Man as it was already in one form or another before the world, was content with anything that might stand for the fulfilment of his philosophical purpose. But he had still in him more than twenty years of vigorous vitality, and, not conscious to himself of any shortcoming, looked forward, now his hands were free, to doing battle for his doctrines. Rather than remain quiet, on finding no notice taken of his latest production, he would himself force on a new conflict with the enemy. Wallis having meanwhile published other works and especially a comprehensive treatise on the general principles of calculus (_Mathesis universalis_, 1657), he might take this occasion of exposing afresh the new-fangled methods of mathematical analysis and reasserting his own earlier positions. Accordingly, by the spring of 1660, he had managed to put his criticism and assertions into five dialogues under the title _Examinatio et emendatio mathematicae hodiernae qualis explicatur in libris Johannis Wallisii_, with a sixth dialogue so called, consisting almost entirely of seventy or more propositions on the circle and cycloid.[16] Wallis, however, would not take the bait. Hobbes then tried another tack. Next year, having solved, as he thought, another ancient _crux_, the duplication of the cube, he had his solution brought out anonymously at Paris in French, so as to put Wallis and other critics off the scent and extort a judgment that might be withheld from a work of his. The artifice was successful, and no sooner had Wallis publicly refuted the solution than Hobbes claimed the credit of it, and went more wonderfully than ever astray in its defence. He presently republished it (in modified