That's just how I read this: You push at the boundary for a few years Until one day, the boundary gives way And, that dent you've made is called a

That's just how I read this: You push at the boundary for a few years Until one day, the boundary gives way And, that dent you've made is called a Ph.D. It seems to me that calling the expansion of human knowledge a Ph.D. implies that those who don't have Ph.D.s have not dented the circle.