The mystifying side of Hegelian dialectic I criticised nearly thirty years ago, at a time when it was still the fashion. But just as I was working at… - Benedictus de Spinoza

Most writers on the emotions and on human conduct seem to be treating rather of matters outside nature than of natural phenomena following nature's general laws. They appear to conceive man to be situated in nature as a kingdom within a kingdom: for they believe that he disturbs rather than follows nature's order, that he has absolute control over his actions, and that he is determined solely by himself. They attribute human infirmities and fickleness, not to the power of nature in general, but to some mysterious flaw in the nature of man, which accordingly they bemoan, deride, despise, or, as usually happens, abuse: he, who succeeds in hitting off the weakness of the human mind more eloquently or more acutely than his fellows, is looked upon as a seer. [...] Such persons will, doubtless think it strange that I should attempt to treat of human vice and folly geometrically, and should wish to set forth with rigid reasoning those matters which they cry out against as repugnant to reason, frivolous, absurd, and dreadful. However, such is my plan.

...The more a man knows about individual objects, the more he knows about God. Translating Spinoza's language into ours, we can say: The more a man knows about himself in relation to every kind of experience, the greater his chance of suddenly, one fine morning, realizing who in fact he is...

According to the seventeenth-century way of thinking, an atheist was by definition a decadent. If there was no God (or, at least, no providential, rewarding-and-punishing God of the sort worshipped in all the traditional religions), the reasoning went, then everything is permitted. So a non-beliver would be expected to indulge in all manner of sensual stimulation... to lie, cheat, and steal...
Spinoza, according to all seventeenth-century interpreters, rejected all the traditional ideas about God; he was indesputably a heretic. Yet his manner of living was humble and apparently free of vice. Then, as now, the philosopher seemed a living oxymoron: he was an ascetic sensualist, a spiritual materialist, a sociable hermit, a secular saint. How could his life have been so good, the critics asked, when his philosophy was so bad?