Meanings of solid substratum in English

Underneath the later concoction of fable is a solid substratum of fact which no serious student can ignore.

While much of this is nothing but the wildest imagining, still there remains a very firm and solid substratum of truth underlying it all.

Also, they have wit, invention and a richly pictorial sense for setting, together with flamboyant attraction of style and a solid substratum of thought.

We have come to that solid substratum acknowledged by Grotius in his great Treatise: "Necessity itself which reduces things to the mere right of Nature."