Steal, Don’t Borrow

of course, thinking it through is important

Not sure I really understand the distinctions here. First of all, no one actually "borrows" anything in art. Borrowing something would imply that you were going to return it at some point, which doesn't really fit with how that scenario works. I think a more appropriate way of thinking about artistic influence is through the concepts of copying and transformation.

Copying is the act of stealing without transformation. In other words, the work is purely derivative. Transformation, on the other hand, is the act of combining your influence(s) and using them as a basis for a new idea. I don't think it makes much of a difference whether this is an intentional or unconscious act. Both copying and transformation have their place in art.

Most artists start out through imitation (copying) and move on to transformation. For example, Keith Richards started out by obsessively copying the styles of American Blues artists, it wasn't until years later that he had absorbed those early influences enough to go on to transform them into his own distinctive style of playing. Same with someone like Picasso. His early work is rooted in traditional realism. Later on he would go on to be heavily influenced by symbolism and African folk art- which ultimately led to Cubism.