Emptiness and experiment are the two main notions of the famous debate about the “invention” of the air pump that took place during the 1660’s and 1670’s. The aim of this article is to focus on Baruch de Spinoza and Robert Boyle’s correspondence, in order to analyze what they understood by Nature, how they thought it could be “known” and to what extent. Keywords Air Pump. Nature. Truth. Science. Common Notions.O vácuo e o experimento constituem duas noções-chave do famoso debate de meados do século XVII em torno da "invenção" da bomba de vácuo. Nossa proposta é revisar a correspondência entre Baruch de Spinoza e Robert Boyle para analisar o que os dois filósofos entendiam pela Natureza, em que medida concebiam que esta podia ser “conhecida”...