Art needs resistance in the materials

I've been familiar with the concept, indeed I've found it a helpful way in to reflecting on artistic process ever since I came across the idea in the theology (theodicy) of Vanstone in Love's Endeavour, Love's Expense. In it Vanstone (without, I think, making a link to Morris -but I may not be recalling aright) explores the artistic enterprise as dialogic between the ideas of the artist and the capabilities and resistances of the materials. He then explores this as an image of the Creator-creation relationship.
Anyway, good to discover it is something penned also by Wm. Morris.

Limitation and Resistance: Why Freedom Is Overrated in Creativity � canalside view: As the textile artist William Morris said, “You can’t have art without resistance in the materials.”