I think the key phrase there is "look beyond symbol" - when you're illustrating something that has lettering, for example, one often starts writing out the letters instead of illustrating the shape of the letters. The same thing commonly happens when drawing eyes - people learn a technique for "how to draw an eye," and when they move on to a full portrait, instead of trying to reproduce or illustrate the image they see before them, they call their internal "draw an eye" function.