Wracking my brain (and the Internet) to find other examples of this "same unto same" belief expressed in ancient philosophy and Platonism in particular, but it's worth noting that sentiments like this were expressed even earlier, in Timaeus. I'm looking in particular at the reference to vision:

When the light of day surrounds the stream of vision, then like falls upon like, and they coalesce, and one body is formed by natural affinity in the line of vision, wherever the light that falls from within meets with an external object. And the whole stream of vision, being similarly affected in virtue of similarity...