Hearing that the Buddha sat like the king of mountains, the stupid among us, in which category I include myself, are liable to strive to sit like a mountain -- bringing to this effort all the abstract knowledge we have accumulated in our brain on such matters as primitive reflexes, Alexander Technique, listening work, Dogen's instructions for sitting-zen, the Buddha's teaching of four noble truths, the flow of chi in Chinese medicine, et cetera, et cetera, et cetera. Striving thus tends to tie us to what we already know -- mainly a faulty sense of where up is, a rubbish heap of bright ideas, and wrong inner patterns of use. Whereas the whole point of sitting like a mountain might be that a mountain never strives to be a mountain and never strives to be anything other than a mountain. A mountain never disturbs itself by failing to accept itself totally as a mountain.
So Buddha sitting like a mountain is not teaching that we strivers should strive to understand. It is teaching that we should categorically NOT strive to understand. It may be that faulty feelings, bright ideas, and wrong patterns of use, all spontaneously drop off just in the moment of not striving itself.