The theory of variable embodiments has been primarily formulated to model ordinary objects as things that change their parts over time. A variable embodiment /f/ is a sui generis whole constructed from a principle f, the principle of a variable embodiment, and it is manifested at different times by different things picked out by such a principle f. This principle is usually clarified as a function that picks out, at any given time the variable embodiment exists, its corresponding manifestation at (...) that time, and it fails to pick out anything at any other time. The first purpose of this article is to examine and refute three natural understandings of such a principle. Specifically, first, we argue against the view that it should be understood extensionally as either a partial function or total function. Next, we provide some motivations to reject the understanding of the principle as a function in intensional terms, where the notion of intension is analyzed in terms of a specific version of a possible world semantics. The second goal of the article is to make it plausible that the principle has an intensional character and, on the basis of the results achieved, to formulate some constraints that an account of such a principle should meet. (shrink)