What does it mean, 'inner' and 'outer trigram' (popup)
Wind below Lake: things never stop anywhere, they move on an on. They come up, arrive at their fullest potential, and go down again. It is useless to fret about this decline, it is an essential part of the entire universe. Make the best use if it, accept it for what it is and acknowledge its worth. In society old age has a big value. Maybe your strength will lessen, but your wisdom has grown. Every situation has its rise and decline, and every phase has its own value.
Ideogram of the hexagram name: the first (upper) character is a big person: big. The second character is a foot on a road and a skeleton over a mouth: a distorted mouth. A description of passing over a mouth or cleft in a mountain.
Dà Guò is a big mountain-pass, it means to go beyond the limit, surplus. A passing which is usually irreversible. It is used for serious transgressions, especially regarding rules, like in a school or army. But also in a positive sense: surpassing others with an asset. Better or smarter. Another meaning is to transfer accounts and the transition from active life to old age.
The 'Great Image' says: a marsh over the trees (or Wind below Lake): Great excess. The noble one stands alone without fear, retreats (or retires) without melancholy.
Hex.28 is the contrast of 27, which is about sustaining and supporting life.
Hex.28 is the change from active life to retirement, or peak to decline, or any inevitable change in life, and accepting it.