Abstract: Mechanism is at the origin of the actual economical conception, based on endless growth. It is founded on Descartes's thought, with its strong distinction between mind and material world, continued by Bacon and Newton (as Latouche points out). Some years before and some years after Descartes, Montaigne and Spinoza respectively proposed significantly different conceptions. The French one, inside a skepticism, enemy of any abstract system claiming to control the real world; the Dutch one proposing a unique substance composing all the universe, id est a sort of rational pantheism. Exploring the meaning of these three philosophical theorizations, expressed at the very beginning of Modern Era (16th and 17th centuries), may help us to understand not only the roots of the present mainstream, but also the premises of alternative ways of thinking, like ours.