A virgin habitat can easily be colonized by a newly arriving species that reproduces rapidly giving a large number of offspring that can be relatively small in size and not of high average fitness. A species living in a habitat that already has full 'residence' of organisms faces high competition and thus delays reproduction, producing fewer offspring that are larger in size and enjoy a higher average fitness.
In order to have plenty of creative ideas 'colonizing' your mind and multiplying, you must first cleans your mind from many of the other competing ideas that colonize it. By doing so, your mind becomes fertile land for creative ideas to keep jumping in and multiplying very rapidly. Eventually, they will fill your mind with good stuff. In contrast, if you keep heavy ideas dwelling in your mind, they will be competing harshly and will not give room for creative ideas to enter. In fact, the old dwelling ideas will reproduce new ideas very scarcely and their reproduction will be delayed.