Henry David Thoreau in the first chapter ("Economy") of Walden touches upon the Zen of the present moment, and the difficulty of speaking explicitly about it:

In any weather, at any hour of the day or night, I have been anxious to improve the nick of time, and notch it on my stick too; to stand on the meeting of two eternities, the past and future, which is precisely the present moment; to toe that line. You will pardon some obscurities, for there are more secrets in my trade than in most men's, and yet not voluntarily kept, but inseparable from its very nature. I would gladly tell all that I know about it, and never paint "No Admittance" on my gate.

(cf. Wherever You Go, There You Are (2008-10-26), Plenty of Time (2009-03-09), ...) - ^z - 2009-09-22