The One Christ: St. Augustine's Theology of Deification
38 Made to be Godly directly and immediately from its source; the reflection ensures the likeness, however unequal. Augustine then goes on to provide a second example in order to illustrate the relationship between equality and likeness, that of two identical eggs. There may be both equality and likeness, but since one egg did not come from the other [quia neutrum de altero expressum est], there is no image. Thirdly, although two specifically different eggs, say one from a chicken and another from a duck, may appear similar to the casual observer, void of any common origin, there can be neither image nor equality.
By insisting that every image demands some level of likeness, but that not every similitudo hearkens back to a relationship of image, Augustine ushered into Latin thought a new understanding of imago, similitudo, and their relationship. Every child will be like the parents she images, for example. However, two children of two different sets of parents do not share the same image, regardless of how alike these two children appear. While every image is naturally like that from which it is copied, not everything which is like something else can be said to be its copy.7 This is how, unlike his predecessors, Augustine is able to attribute a divine "likeness" to all that exists and, so defined, similitudo becomes a much more inclusive term than imago.8 This is key. Image has to do with a common source resulting in shared qualities, but likeness and equality are relational terms having nothing to do with origin or the relationship between existents. It follows that since "similitude is more [amplius] than image," there can be no image which is unlike the source from which it comes.9
7. Cf. Gn. litt. imp. 16.57. 8. R. A. Markus says he has "looked in vain for any precedent for [this widening of "likeness"] even in the works of [Augustine's] Latin predecessors. I can only conclude that his analysis of the meanings in question is a product of his own logical acumen, brought to bear on the language he spoke and wrote"; "<<Imago>> and <<similitudo>> in Augustine," Revue des études augustiniennes 10 (1964): 125–43; 126–27.
9. qu. 3.4, lines 49-50; CCL 33.277 (dated between 419 and 420).