In this paper, I outline the systematic deduction of the necessary relationship between the I and the world in Fichte's Jena Wissenschaftslehre as well as the status of the world to which the I is necessarily related. Using the interpretation of the Anstoß and the thing in itself, I present the Wissenschaftslehre as a consequent and completed critical transcendental philosophy that shows in a systematical manner the boundaries of our cognition.