In the times when King Wen lived, having a permanent home was paramount and a huge blessing. A big solid mountain was like a promise that it would last forever. It can be a house with your family, or a farm with people and animals, or a country under your reign, but having a home means having responsibility. For a good happy home that also means there is love involved, and then it comes close to a mandate, a responsibility bestowed by 'the gods'.
In hexagram 11, the lines 2 and 5 are about responsibility towards the land and towards the people and future of this home "for better for worse, for richer for poorer, in sickness and in health".
Mount Tai is the symbol of all this. From the home created by loving responsible parents to the one reigned by a good king.
Meanings of TAI: Grand, great, eminent, supreme, excessive, arrogant, spread out and reach everywhere, quiet, ease, good luck, effortless, honorable, prosperous, too much, exaggerated, lofty.