Approach begins with two strong lines rising into four yielding ones, and the first of them does not rise alone. Legge's translation shows its subject advancing in company with the line above, and makes good fortune conditional on firm correctness, while the Little Symbolism grounds that fortune in something simpler still: the will is set on doing what is right. Neither strength nor company is what secures the outcome here. The direction of the intention behind the advance is.
Dui, the marsh, forms the lower trigram, and the earth of Kun lies above it, so the hexagram pictures something drawing near from below to what stands over it. This line is the first stroke of that movement, strong and correctly placed in an odd position, at the point where the approach has begun but has met nothing yet. The two strong lines at the base are the growing element in a figure otherwise composed of yielding, which is why the text watches their conduct so closely.
The condition attached is worth reading precisely. Firm correctness is not the same as force, and the commentary declines to praise the advance itself, praising instead the rightness of what the advance is set on. A movement that begins in company and in the right direction is what this hexagram asks of its opening, and everything the later lines describe depends on it.