Both seem to be only alternatives - yet each are impossible. If the species 'man' or genus 'animal' were a reality, it would be one single reality. Man' and 'animal' are common to many and one at the same time. Man' is common to many individual men.
Animal is common to many species.
Genus and species constitute the very substance of the things to which they are common. As conceptions 1. Concepts either correspond to reality or do not. Concepts cannot correspond to reality because of A. above. True concept can be formed apart from a body 3.