For man’s nature, especially his mental nature, has a spontaneous tendency to give a favourable explanation for everything he thinks, feels, says and does. It is only by observing these movements with great care, by bringing them, as it were, before the tribunal of our highest ideal, with a sincere will to submit to its judgment, that we can hope to form in ourselves a discernment that never errs. For if we truly want to progress and acquire the capacity of knowing the truth of our being, that is to say, what we are truly created for, what we can call our mission upon earth, then we must, in a very regular and constant manner, reject from us or eliminate in us whatever contradicts the truth of our existence, whatever is opposed to it. In this way, little by little, all the parts, all the elements of our being can be organised into a homogeneous whole around our psychic centre.
This work of unification requires much time to be brought to some degree of perfection. Therefore, in order to accomplish it, we must arm ourselves with patience and endurance, with a determination to prolong our life as long as necessary for the success of our endeavour.
Ref: On Education