At the age of forty he was, for the first time, introduced to the works of Euclid, and at once 'fell in love with geometry,' being attracted, he says, more by the rigorous manner of proof employed than by the matter of the science. (Mathematics... were then only beginning to be seriously studied in England. Hobbes tells us that in his undergraduate days geometry was still looked upon generally as a form of the 'Black Art,' and it was not until 1619 that the will of Sir Henry Savile, Warden of Merton College, established the first Professorships of Geometry and Astronomy at Oxford.)

Foremost among his friends stands Francis Bacon, who 'loved to converse with him,' and employed him on the translation of some of the famous Essays... into Latin. This connection can be shown to belong to the years 1621-6 when Bacon, after his political disgrace, was devoting himself entirely to scientific work... The influence of Bacon, however, has left no trace on Hobbes's own matured thought. He... has no place for 'Baconian induction' in his own conception of scientific method. Bacon's zeal for experiment, the redeeming feature in an otherwise chaotic scheme of thought, is entirely alien to the essentially deductive and systematic spirit of the Hobbian philosophy.

The first-fruits of... renewed interest in learning was an English translation of Thucydides, published in 1628-9, for the purpose, as Hobbes said at the time, of educating his readers in the true principles of statesmanship. Afterwards, when his absolutist political theories had been fully developed, he wished it to be believed that his real object had been to warn Englishmen against the dangers of democracy, by showing them how much wiser a single great statesman is than a multitude.

The long life of Thomas Hobbes covers almost the whole of the most critical period alike in the growth of modern science and in the development of the British Constitution. Born in the year of the Armada, Hobbes did not die until nine years before the great Revolution which finally determined the question whether the British Islands should be ruled constitutionally or absolutely. He lived through the Stuart attempt to convert England into an absolute monarchy, the Puritan revolution and great Civil War, the political and ecclesiastical experiments of the Long Parliament and of Cromwell, the restoration of the exiled line, and the beginnings of modern Whiggism and Nonconformity. Still more remarkable were the changes which came over the face of science during the same period. When Hobbes entered the University as a lad, the sham Aristotelianism of the Middle Ages was still officially taught in its lecture-rooms; before he died, mechanical science had been placed on a secure footing by Kepler, Galileo, and Descartes, the foundations of the scientific study of physiology and magnetism had been laid by Harvey and Gilbert, the Royal Society for experimental research into nature had been incorporated for more than a generation, analytical geometry had been created by Descartes, and the calculus by Leibniz and Newton, while it was only eight years after his death that the final exposition of the new mechanical conception of the universe was given by Newton's Principia. It is only natural that a philosopher who was also a keen observer of men and affairs, living through such a period of crisis, should have made the most daring of all attempts to base the whole of knowledge on the principles of mechanical materialism, and should also have become the creator of a purely naturalistic theory of ethics and sociology.

At the core of Hobbes’s theory of political authority is the provision of security. “The end of Obedience is Protection,” Hobbes insists in chapter 21 of Leviathan. The Obligation of Subjects to the Soveraign, is understood to last as long, and no longer, than the power lasteth, by which he is able to protect them.” This is because “the right men have by Nature to protect themselves, when none else can protect them, can by no Covenant be relinquished.”6 The king’s rightful authority is rooted in his capacity to protect his subjects. As a result, their obligation to obey him, unqualified as it is while it lasts, expires with the king’s ability to protect them.Hobbes spelled this out even more perspicaciously in his discussion of conquest—with clear implications for what was at stake in the Engagement controversy. A person is conquered not by being slain or imprisoned. (In the latter case “he is still an Enemy, and may save himself if hee can.”) Rather, “he that upon promise of Obedience, hath his Life and Liberty allowed him, is then Conquered, and a Subject; and not before.” The long and short of it was that once Parliament had replaced the king as protector of the people of England, they owed Parliament their unqualified allegiance. Engagement was therefore legitimate. Indeed, in the circumstances after 1649, it was obligatory. And it would follow, a fortiori, that should Parliament lose the capacity to provide protection, then the obligation to Engage would cease as well.In this way, Hobbes could counsel Charles’s supporters to promise allegiance to Parliament, but they could do it in a manner that would not compromise their ability to support the king in the event of a restoration. As it turned out, making this move alienated Hobbes from many royalists—even though he offered them a doctrine that promised to get them out of a tight spot and hedge their bets for the future. Their attachment, it seems, was to Charles himself, or at least to the institution of the monarchy.

When Hobbes referred to the dire state of human beings in having ‘nasty, brutish and short’ lives, he also pointed, in the same sentence, to the disturbing adversity of being ‘solitary’. Escape from isolation may not only be important for the quality of human life, it can also contribute powerfully to understanding and responding to the other deprivations from which human beings suffer. There is surely a basic strength here which is complementary to the engagement in which theories of justice are involved.

Hobbes himself had experienced this truth in the terrible times of civil war, because then all legitimate and normative illusions with which men like to deceive themselves regarding political realities in periods of untroubled security vanish. If within the state there are organized parties capable of according their members more protection than the state, then the latter becomes at best an annex of such parties, and the individual citizen knows whom he has to obey.

It is a remarkable fact that, in a history extending over nearly twenty-five hundred years, a considerable part of the most significant writing on political philosophy was done in two periods of only about fifty years each and in two places of quite restricted area. … The Second place was England, and the period was the half century between 1640 and 1690, which produced the works of Hobbes and Locke, together with the works of a host of lesser figures.

The reasoning of Caligula agrees with that of Hobbes and Grotius.

The study of politics is a form of natural history. Thomas Hobbes loathed Aristotle’s politics, and in Leviathan followed Plato in modeling politics on geometry; but he admired Aristotle’s biology. One consequence of that “biological” style is important, not only because it was at odds with Hobbes’s—and Plato’s—hankering after political geometry. Aristotle claimed that political analysis should aim only “at as much precision as the subject matter permits.” Political wisdom cannot aspire to the precision of geometry, and must not pretend to. Aboriculture suggests an analogy: most trees grow best in firm soil with a moderate water supply; a few thrive with their roots in mud and water.