Sangen shugi (三現主義): the principle of the three actuals. Genba, the actual place. Genbutsu, the actual thing. Genjitsu, the actual facts. Problems are solved by observing the thing at the place, not at a desk.
Hyakubun wa ikken ni shikazu (百聞は一見に如かず): a hundred hearings are not worth one seeing. Seeing something once with one’s own eyes teaches more than hearing about it many times.
Tatami no ue no suiren (畳の上の水練): swimming practice on the tatami. Practice that is all theory and of no real use.