“Know thyself.”....the most dangerous thing in the realm of knowledge is to grasp these words erroneously and today this occurs only too frequently. Many people construe these words to mean that they should no longer look about the physical world, but should gaze into their own inner being and seek there for everything spiritual. This is a very mistaken understanding of the saying, for that is not at all what it means.
We must clearly understand that true higher knowledge is also an evolution from one standpoint, which the human being has attained, to another which he had not reached previously. If a person practices self-knowledge only by brooding upon himself, he sees only what he already possesses. He thereby acquires nothing new, but only knowledge of his own lower self in the present meaning of the word. This inner nature is only one part that is necessary for knowledge. The other part that is necessary must be added. Without the two parts, there is no real knowledge. By means of his inner nature, he can develop organs through which he can gain knowledge. But just as the eye, as an external sense organ, would not perceive the sun by gazing into itself, but only by looking outward at the sun, so must the inner perceptive organs gaze outwardly, in other words, gaze into an external spiritual in order actually to perceive.
The concept “Knowledge” had a much deeper, a more real meaning in those ages when spiritual things were better understood than at present. Read in the Bible the words, “Abraham knew his wife!” or this or that Patriarch “knew his wife.” One does not need to seek very far in order to understand that by this expression fructification is meant. When one considers the words, “Know thyself,” in the Greek, they do not mean that you stare into your own inner being, but that you fructify yourself with what streams into you from the spiritual world. “Know thyself” means: Fructify thyself with the content of the spiritual world!