I would like to ask on the top of seriosity. Please, read it twice: How could "taoism or buddhism" have had "separate origins" and still stayed "the same thing"!? as Blizzardry said. I think and believe it's rather obviously they have the one origin. What evidence do we need, if such an obvious is given up? If there can be any unsure feeling, it must be very faint.
And it may be proved by DrumR's "Dhyanna = Ch'an = Zen = Meditation" conception. And English might change the pronounciation, 'cos of its strange writing tradition (with so-called 'deaf' letters and so on). The analysis of these terms might have proved even for a hereditary skeptic they're all connected.
Sanskrit "dhyana" stands for "an occult meditation". It isn't just a meditation with its relaxation and so on. It's the hardest labour of mind, of soul if you wish. Very little people can practice real dhyana. And in this connection, maybe it's not out of place to remind Indian dhyani-buddhas (if I correctly wrote). They're quite high level of buddhas. If you remember, there exist the amida-buddha (or Mahavishnu), dhyani-buddhas, manushya-buddhas etc. Dhyani-buddhas are very respective. Gautama is traditionally understood as a first manushya-buddha on the Earth.
"Chan"'s Chinese form of dhyana. They usually shorten words, to write them with only hyerogliphic I guess. Because real Chineseficated dhyana would be, if I'm not mistaken, Chan'na.
English "Zen" is Japanese "Dzen". Wikipedia, as you know, links Dzen with "zazen — in the attainment of awakening". Buddha takes its origin from 'budh' - to awake, doesn't it?
And as for the "meditation". "Meditation is a mental discipline by which one attempts to get beyond the conditioned, "thinking" mind into a deeper state of relaxation or awareness," says wiki. I don't know, maybe I've been misinformed when was being taught English, but I though "relaxation" is when one does nothing, just nothing. When we're tired, we need some relaxation. And meditation's an exercise of mind. It's coler to a "deeper state" of concentration, than relaxation. Anyway, dhyana is a level of meditation. Patanjali call it so: the fourth grade of occult meditation. I'd indeed agree with Blizzardry that "meditation practise and philosophy differ, you can see". And far not everyone fits to the practice, but to philosophy each seems to fit. Why? Because people have different abilities - anyone can play bascketball, but my height doesn't allow me to. And I stricktly disagree that "Actually, deep down, an experience of the divine is the same whoever feels it, Moses, Buddha or John Lennon." Yes, "whoever feels it", but to feel it one must go long and hard way. Moses and Buddha were fit, but the latter...