Whether or not Lao-tze meant it, he here endorses Kant's doctrine of the a priori, which means that certain truths can be stated a priori, viz., even before we make an actual experience. It is not the globe trotter who knows mankind, but the thinker. In order to know the sun's chemical composition we need not go to the sun; we can analyze the sun's light by spectrum analysis. We need not stretch a tape line to the moon to measure its distance from the earth, we can calculate it by the methods of an a priori science (trigonometry).