The question of identity and diversity has been approached by ancient and medieval philosophers via Logic (definiendum's genus proximum and differentia specifica), or Physics (matter as the principle of individuation within the same species), or Theology (the unity of essence and multiplicity of persons or hypostases in Christianity). There is no place in these contexts for any discussion of the personal identity of each and every person alone. The identity of the definiendum is the same as that of the species'; not the individual's, the individual identity is physical; not personal, and the identity of the divine essence does not contradict the multiplicity of persons. In this respect, the philosophical authenticity of John Locke lies in his transformation of the issue of identity from the theological polemic to the context of practical debate. He created a different context that embraces the individual identity, liberating it thereby from being totally cancelled out in species, indebted to material composition, and from dependence on the essence. With Locke, personal identity has become both dependent on consciousness and the center of legal and moral responsibility.