Born at Digne, he was first a Canon in his native town, then Professor of philosophy at Aix, then, later, of astronomy and mathematics at the Collège de France. His education in a mainly humanist mould played a decisive role in making his choices in a philosophical context. In his readings of Seneca, Plutarch, Cicero and Lucretius, as well as Erasmus, Charron and Montaigne, Gassendi drew ideas and suggestions which show themselves to be extremely influential in the formation of his own mature philosophical system. These authors' works lead Gassendi towards a structure of thought strongly inclined towards empiricism and streaked with scepticism, in addition to his criticism of aristotelian and scholastic metaphysics.

The need to flee from the aristotelian tradition let him turn towards other thinkers, and, in particular, towards Epicurus. Gassendi recognised in the Greek thinker's atomism a particularly rich research programme for the nascent experimental science. The discoveries performed by the microscope in those years were interpreted, by Gassendi and many of his contemporaries, as a serious validation of atomism, and contributed to the enormous success which the Canon of Digne's theses had with European intellectuals of the day.

Gassendi's research is of outstanding interest above all in the fields of astronomy and dynamics. In the former, he carries out accurate and long-term observations, which he recorded in minute detail. In the field of the physics of motion, on the other hand, his work signals, above all, the confirmation of the science of motion worked out by Galileo.

Gassendi developed an interesting notion of space, which he considered as an infinite three-dimensional void, absolutely immobile and homogeneous, which exists in itself, even in the absence of bodies to define the parts. This metaphysical intuition in some way heralds the Newtonian notion of "absolute space". It was shared, too, by other figures in the debate over the existence of the vacuum in the first half of the seventeenth century (Otto von Guericke, for example). In opposition to cartesian physics - which identifies matter and extension, rejecting immediately even the possibility of an "empty space" - Gassendi's notion held that the "void" was acceptable in the very idea of space.