Gassend wears a black skull-cap and a white collar. He has grey hair, a moustache and a tiny beard. Inscribed around the oval is 'Effigies Petri Gassendi,illivs philosophi qui orbem terrarum altissime illuminavit'. The form of the inscription implies a posthumous portrait, and the whole style of work suggests a copy from a contemporary engraving.
Pierre Gassend or Gassendi, the French philosopher, scientist and mathematician, was born at Champtercier and educated at Digne and the University of Aix. In 1612 he was appointed Lecturer in Theology at Digne and in 1617 Professor of Philosophy in the University of Aix, and in 1645 he was elected to the Professorship of Mathematics in the College Royal at Paris.
Gassend's philosophical theories brought him into friendly conflict with Descartes. The reviver of atomism and an advocate of empirical realism, he was opposed to a blind acceptance of the Aristotelian system, which he examined in his 'Exercitationes paradoxicae adversus Aristoteleos'. As a natural philosopher he stressed the importance of experimental research, but he added little to current knowledge of physical science. His works on mathematics and astronomy, on the other hand, form valuable contributions to the subject of the history of science. His 'Institutio Astronomica' gives a lucid description of the advance of science in his day, while he lives of Tycho Brahe, Copernicus, and Regiomontanus are among the finest examples of 17th-century biography.