THE SIGN:

Trigram Sun, the Gentleabove Sun the Gentle, Wind, Wood
Trigram K'an, the Abysmalbelow K'an the Abysmal, Water

Wind blowing over water disperses it, dissolving it into foam and mist. This suggests that when a man's vital energy is dammed up within him (indicated as a danger by the attribute of the lower trigram), gentleness serves to break up and dissolve the blockage.