The sediments of the past are many miles in collective thickness: yet the feeble silt of the rivers built them all from base to summit.
In order to acquire a growing and lasting respect in society, it is a good thing, if you possess great talent, to give, early in your youth, a very hard kick to the right shin of the society that you love. After that, be a snob.
He knew a lot about his grandparents - and perhaps he feels he's been endowed with abilities to go into people's heads who are long dead - but, to a certain extent, he's making it up.