finding the Way
Boddiharma also said that only a tacit understanding is sufficient. By this I think that he meant when we try to over-analyze something that is as inherently deep and mystical as "zen" or "Tao," we immediately get into trouble because by its very nature, it is not completely understandable.
Words themselves are part of the illusion that we are trying to overcome.
Our intellectual attempts at understanding the Tao are just the first phase of learning. If we could actually understand it, there would be no more mystery. But, in reality such an intellectual understanding is impossible.
The ancients realized that we could gradually gain a deeper, true understanding of Tao by shutting off our internal dialogue through meditation or other esoteric practices that allow us to return to the level of "direct experience," that is, experiencing phenomenon without verbal coloration.
Therefore, IMHO, if an aikido instructor simply has a tacit understanding of Tao, I believe that this is sufficient for him to teach the "art," and not simply the "technique" or waza.
In the end we find out that we are the Way, and that our journey through life is the teacher. But only the humble can fully gain from its lessons.