来　行　乗　大　小

来 began as a pictograph of a wheat plant arriving from the west. Grain that came from afar became the symbol of something arriving from a distant place — giving this character the meaning 'to come'.

行 is a pictograph of a crossroads — the left half (彳) shows a person stepping forward, the right (亍) shows the other foot's step. Together: two feet alternating at a junction = to go, to travel.

乗 originally showed a person (大) standing on top of a tree (木) with arms spread for balance — the image of someone climbing up and mounting. A person elevated above a base perfectly captures the act of boarding a vehicle.

大 is a person standing with arms and legs spread wide — taking up as much space as possible. This posture of maximum expansion is the universal human gesture for bigness and greatness. Root of 大学 (university), 大切 (important), and more.

小 is the visual opposite of 大. Where 大 is a person spread wide, 小 shows three tiny dots or grains — things so small they scatter. Some read it as a dividing line with tiny fragments falling away on each side — the result of cutting something into minute pieces.