Well, I'm quite certain the source for the Baisc Blocks is going to be well received (LOL) by anyone looking to punch at the opinion put forward , but it came from a website that specializes in travel:http://www.imperialtours.net/chan_buddhism.htm
Give that as it way, it's also two-way street, as it would appear that neither position can be proven with any more certainty, other than as a practitioner it is assumed that we must
... or example, the following statement borrowed from Wiki with good citations:The historical records required for a complete, accurate account of early Chán history no longer exist. Theories about the influence of other schools in the evolution of Chán are widely variable and rely heavily on speculative correlation rather than on written records or histories. Some scholars have argued that Chán developed from the interaction between Mahāyāna Buddhism and Taoism.
 Broughton 1999:138
 Cleary, Thomas (2005). Classics of Buddhism and Zen: Volume One. Boston, MA: Shambhala publications. p. 250.
 Maspero, Henri (1981). Taoism and Chinese Religion. University of Massachusetts. p. 46.
There are plenty of red herrings, no argument, but is it really any different than clinging so tightly to what's handed down to us within Buddhism (or any tradition for that matter), that it's the god honest truth, a sacred cow above approach, where we not only fail to see the tree standing before us, but are more likely to be oblivious to the potential of it falling over and squashing us like a bug?
Also, I never inferred that there is some "Universal Mind" to return to, only that all spiritual traditions borrow from their predecessor, that no branch of Buddhism, or any other tradition, has ever been immune from such. For example, try to imagine a Buddhist tradition without having first passed through the pre-exisiting tenents of a Brahmic society and culture, sociocentric underpinnings, ect.
Now try imagining a Ch'an without having passed through the pre-exisiting tenents of a Chinese society and culture, sociocentric underpinnings, ect.
In other words, we talk the talk of interconnectedness, but in most cases it's a shell game when we fail to give credit where credit's due.... like the song goes, "moss can't grow on a rolling stone"