Part of foolishness, or what looks like foolishness, is stealing ideas from a different domain. Someone in economics, for example, may borrow ideas from evolutionary biology, imagining that the ideas might be relevant to evolutionary economics. A scholar who does so will often get the ideas wrong; he may twist and strain them in applying them to his own discipline. But this kind of cross-disciplinary stealing can be very rich and productive. It's a tricky thing, because foolishness is usually that--foolishness. It can push you to be very creative, but uselessly creative. The chance that someone who knows no physics will be usefully creative in physics must be so close to zero as to be indistinguishable from it. Yet big jumps are likely to come in the form of foolishness that, against long odds, turns out to be valuable. So there's a nice tension between how much foolishness is good for knowledge and how much knowledge is good for foolishness.
Without further ceremony, the rhetoric here serves well to alert you to the value of jumping. To jump from one field of knowledge to another, to leave your camp and meddle with the affairs in another camp. Probing into territories of weakness is a strategy i have been following since age 2. So i like to read that a guru can make sense of it. What he is saying in that passsage is that surprises are likely to come from the outlines.
However I´d rather rename cross-disciplinary stealing to cross-disciplinary healing. Stealing an idea presupposes that someone else owns it. It is true that you can own an idea by the amount of links that lead to you in regard to that idea. But when someone uses that idea, those links don´t get removed. They would rather be extended. Eventually someone adds the missing link, or triggers a whole new set. So, owning an idea comes through graciously giving it away freely.
Looking at a block of knowledge, being in front of it and being behind it after passing through it, are much like the same positions. Either position is tricky to start from. Attempting to know something and believing to know a masterfully lot is a situation much like a doctor-patient relationship. The doctor can only be healed by having patients. And there is nothing foolish about being a patient. Being sick with curiosity can hardly be called foolish. You don´t steal from your doctor. You give him the pain that he craves. So take the pills, but don´t use them as prescribed. That “can be very rich and productive”.