He often travelled to meet great scientists, which made him an important mediator. This is especially true for mathematicians such as Pierre Gassendi, Gilles Personne de Roberval, Blaise Pascal und Pierre de Fermat. To tell Mersenne of a discovery was like publishing it. He told Gassendi to reply to the "Meditations" of Descartes. Mersenne gave Huygens the idea of using a pendulum to measure time. This led to the development of pendulum clocks.