It seems to me that, in every culture, I come across a chapter headed Wisdom. And then I know exactly what is going to follow: Vanity of vanities, al… - Ludwig Wittgenstein

an inner process stands in need of outward criteria

At the basis of the whole modern view of the world lies the illusion that the so-called laws of nature are the explanations of natural phenomena. So people stop short at natural laws as at something unassailable, as did the ancients at God and Fate.
And they both are right and wrong. But the ancients were clearer, in so far as they recognized one clear conclusion, whereas in the modern system it should appear as though everything were explained.

Here it can be seen that solipsism, when its implications are followed out strictly, coincides with pure realism.