dao = head, leader (headdress of warrior), and go, walk (foot)
天下之至柔驰骋天下之至坚
Chapter 43:1 - "The softest things of the world overcome the hardest things in the world."
cheng = run, gallop (man on galloping horse) tian = under heaven, sky xia = rule, dominate
to "overcome"
source: http://en.wikipedia.org/wiki/Tao
and http://www.yellowbridge.com/onlinelit/daodejing.html