According to Donald Baxter's Aspect Theory of Instantiation, a particular instantiates a universal when an aspect of the particular is also an aspect of the universal. According to an improved version of this account, this happens when the universal itself is an aspect of the particular.
We can accept Plato's "ingredient principle" when we replace the distinction between things and properties with a slightly different one.
The Aristotelian doctrine of four causes naturally arises from the combination of the two distinctions (a) between things and changes, and (b) between that which potentially is a certain thing or change and what it potentially is.
Virtues are not character traits of individual agents, but generic ways of acting; this is why Anscombe found them important, and this is how Aristotle talks about them.
When Descartes calls the soul of a human being an immaterial substance, he does not contradict the Aristotelian doctrine according to which the soul of a person is the substantial form of her body.
Descartes uses 'conscientia' in the traditional sense, roughly meaning 'moral conscience'.
I use Austin's distinction of two directions of fit in order to explain how a priori knowledge is possible.