The line, the details: Piano or pianissimo, reserved and gentle. Or amabile, moderato, vivace: lovely, moderate or vivid.
Piano works like an all-round instrument. Piano realizes personal ideas. PIANO, the music instrument. “Piano!” means holding on: Wait a second! Piano also means floor and level, plan, layer and wing, silent and simple. Piano, pianissimo: The music plays very gently. PIANO, the plan.