How man is engaged in this work (Steiner is talking here about the work of the ego on one’s own soul) becomes evident if one compares a person who still surrenders himself to his lower passions and so-called sensual lust, with a noble idealist. The latter develops out of the former if he rids himself of certain low inclinations and turns toward nobler ones. In doing so he has worked on his soul, ennobling and spiritualizing it out of his ego. The ego has become master within the soul-life. This can be carried so far that no desire, no enjoyment can gain entrance into the soul without the I being the power that makes the entrance possible.
In this way, the whole soul now becomes a manifestation of the I, as this was previously the case with the consciousness soul alone. In fact, all cultural life and all spiritual human endeavor consists in a work that has as its aim this rulership of the ego. Every human being living in the present age is engaged in this work whether he wants it or not, whether he is conscious of it or not.
Source: Rudolf Steiner – GA 13 – An Outline of Occult Science: II: THE ESSENTIAL NATURE OF MANKIND
Translated by Maud and Henry B. Monges and revised for this edition by Lisa D. Monges