If you intend to study the mind, you must have systematic training; you must practice to bring the mind under your control, to attain to that consciousness from which you will be able to study the mind and remain unmoved by any of its wild gyrations. Otherwise the facts observed will not be reliable; they will not apply to all people and therefore will not be truly facts or data at all.
Swami VivekanandaJust as I sit down to meditate, all the vilest subjects in the world come up. The whole thing is nauseating. Why should the mind think thoughts I do not want it to think? I am as it were a slave to the mind.
Swami Vivekananda