Thomas Aquinas,
Summa Theologiae — Question 93 - THE END OR TERM OF THE PRODUCTION OF MAN…
“ But equality does not belong to the essence of an image; for as Augustine says (QQ. 83, qu. 74) : "Where there is an image there is not necessarily equality," as we see in a person's image reflected in a glass. Yet this is of the essence of a perfect image; for in a perfect image nothing is wanting that is to be found in that of which it is a copy. Now it is manifest that in man there is some likeness to God, copied from God as from an exemplar; yet this likeness is not one of equality, for such an exemplar infinitely excels its copy. Therefore there is in man a likeness to God ”
