Based on an overview of Lacan's theory, we discuss some of Lacan's concepts that we consider to have contributed to modern psychiatry. It is necessary to comment on the quality of the enigmatic aspect of the mental activity (not only the pathological activity but also the ordinal activity) to grasp accurately the pathology of mental states. In schizophrenia, we mention the dominance of signifiers, which Lacan considered the basis of psychic phenomena, and explain the pathological state called "incomprehensive". Furthermore, we discuss psychogenic pathologies, especially "neurosis", in view of the duality of psychogenesis and of "après coup" and explain what comprehensibility is. Finally, we introduce a discussion about autism spectrum disorder (ASD) among Lacanians in France and explain how the pathology of ASD differs from those of the two pathologies described above.
 Author's abstract