This article, focusing on the inclusion- in- notion principle in the philosophy of Leibniz and its reading by Gilles Deleuze, claims that Deleuzian approach in the philosophical critique of the philosophy of Leibniz leads to recreation of the concept of the fold and the subject of fold in Leibnizian thought. To achieve this goal, we initially provide an in-depth study of this principle and its related principles in his philosophy and place emphasis upon their ontological aspect. Then we organize Deleuze’s (...) reading of Leibniz’s philosophy around the inclusion-in-notion principle and picture the world of foldings as the outcome of such reading. We make an effort to clarify how the reading of this principle by Deleuze creates new possibilities in the philosophy of Leibniz and gives birth to the Leibnizian- Deleuzian subject of the fold. Therefore, in the last step, we study this Leibnizian- Deleuzian subject and its characteristics, which is the result of the inclusion- in- notion principle. (shrink)