道可道,非常道;名可名,非常名。
无,名天地之始;有,名万物之母。
故常无欲,以观其妙;常有欲,以观其徼。
此两者,同出而异名,同谓之玄,玄之又玄,众妙之门。
http://my.tv.sohu.com/us/6070475/30775304.shtml
Basically, the names given to objects are there to explain their properties, the name has no meaning itself, and is an invention of humans.
That Wu is the beginning of all things
You as that which has already physical form.
Should avoid excessive outward desire, to observe better the inner workings of the self.