The following considerations revolve only on one purpose: to demonstrate the correlation that exists just in the principles of two versions of the doctrine, the Science of Knowledge. The writen paper aims to give an account of the internal unity in the two versions of the scientific system and the existing continuity of external character in the doctrine itself; thus, the concept of doctrine and system or science is differentiated. On the other hand, the internal unit is responsible for justifying the difference, similarity and equality between the concepts Thathandlung (1794) and absolute (1804). By outlining in general terms how the doctrine and the system are assembled and continued in the two scientific versions presented here, it is intended to give a global vision of the concept of the Science of Knowledge.