Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Sabatier principle is a qualitative concept in chemical catalysis named after the French chemist Paul Sabatier. It states that the interactions between the catalyst and the substrate should be "just right"; that is, neither too strong nor too weak. If the interaction is too weak, the substrate will fail to bind to the catalyst and no reaction will take place. On the other hand, if the interaction is too strong, the catalyst gets blocked by substrate or product that fails to dissociate.