 Krishna tells Arjuna that one who performs his duty without association with the modes of material nature, without false ego, with great determination and enthusiasm ( धृत्युत्साहसमन्वितः), without wavering in success or failure is said to be a worker in the mode of goodness; this means that such a person is always enthusiastic till the completion of such work.Ramana uses the word, "uran" to refer to the strength of will, self-control or knowledge or to mean specifically strength of conviction to know oneself.Aurobindo recalls to mind the combined working of the four great instruments of Yoga for gaining "Yoga-siddhi" or perfection in yoga, viz., "śāstra" i.e.