In Western Philosophy, the mind-only school (known in the U.S. as “Idealism” or specifically “ontological idealism”) is generally understood in terms of Descartes’ Daemon, that is, an uber-skeptical viewpoint wherein the only thing Descartes believed he could be certain of was that he was a thinking thing, because even though he could be tricked into thinking he had a real physical body, he could not then be tricked that he *thought* he had a physical body.  In any case, Descartes was not an Idealist but a Dualist because he made the subsequent leap that he wasn’t the only entity inhering in the world, and thus he believed there was a thinking substance which he possessed via a physical body, while others possessed their own thinking substances via their own physical bodies.

That leap is not necessary.  To believe all of reality is a manifestation of your own mind - the track Descartes was initially on - we can call small-mind Idealism (in contrast to what we can call big-mind Idealism, discussed later).  In small-mind Idealism (simply “Idealism” henceforth, unless context requires), “bodies” and “material” come from the mind alone.  The logic of Idealism is such that any physical activity (eating, for example) is *consistent* within its own framework - the act of eating comes from the mind, including all the “physical” accoutrements of eating.

The activity of birth, however, is different.  Why do I single out birth as an activity fundamentally different from, say, eating?  Because only birth is *inconsistent* with the logic of Idealism.  Eating comes from the mind.  Fine.  But why should the mind be envisioned as coming from a physical body?  That is an inconsistency which Idealism must deal with, and to my knowledge, no one has ever done so.  A possible way out would be to posit that we are really conscious before we are conceived, and that conception itself is not really a conception at all.  If anyone would like to take up this argument in the context of small-mind Idealism, and tell me what conception/birth then is, please do.

This might, however, be accomplished if we move from small-mind to big-mind Idealism.  Big-mind Idealism might say something like, it is a mistake to think of your own consciousness as yours, but just a part of a bigger consciousness, and “birth” is just a temporary separation of your consciousness from the larger whole.  But whereas in small-mind Idealism it was easy to refute a base physical reality because it was “all in your head”, in big-mind Idealism this is not trivial, because there are other perspectives outside your consciousness by definition.  And that distinction is inconsistent with Descartes’ Daemon, where only your own consciousness was certain.  That leap needs to be explained.  And if birth, as I mentioned, is the crux on which that explanation turns, then I am even more justified in calling it out as a philosophically demanding activity.

There are parts of big-mind Idealism I find attractive.  It even sounds Buddhist in some regards.  But I prefer, and I think Buddhism is more in harmony with, ontological materialism than any form of Idealism.  And we can have that discussion another day :)