The Teaching of the Buddha has six supreme qualities: Svākkhāto (Sanskrit: Svākhyāta "well proclaimed"). The Buddha's teaching is not a speculative philosophy but an exposition of the Universal Law of Nature based on a causal analysis of natural phenomena. It is preached, therefore, as a science rather than a sectarian belief system. Full comprehension (enlightenment) of the teaching may take varying lengths of time but Buddhists traditionally say that the course of study is 'excellent in the beginning (sīla – Sanskrit śīla – moral principles), excellent in the middle (samādhi – concentration) and excellent in the end' (paññā - Sanskrit prajñā . . . Wisdom). Sandiṭṭhiko (Sanskrit: Sāṃdṛṣṭika "able to be examined"). The Dhamma is amenable to scientific scrutiny and is not based on faith alone. It can be tested by personal practice and he who follows it will see the result for himself by means of his own experience. Akāliko (Sanskrit: Akālika "timeless, immediate"). The Dhamma is able to bestow timeless and immediate results here and now, for which there is no need to wait until the future or next existence. The dhamma does not change over time and it is not relative to time Ehipassiko (Sanskrit: Ehipaśyika "which you can come and see" — from the phrase ehi, paśya "come, see!"). The Dhamma invites all beings to put it to the test and come see for themselves. Opanayiko (Sanskrit: Avapraṇayika "leading one close to"). Followed as a part of one's life the dhamma leads one on to liberation. In the "Vishuddhimagga" this is also referred to as "Upanayanam." Paccattaṃ veditabbo viññūhi (Sanskrit: Pratyātmaṃ veditavyo vijñaiḥ "To be personally known by the wise"). The Dhamma can be perfectly realized only by the noble disciples (Ariyas) who have matured in supreme wisdom. Knowing these attributes, Buddhists believe that they will attain the greatest peace and happiness through the practice of the Dhamma. Each person is therefore fully responsible for himself to put it in the real practice. Here the Buddha is compared to an experienced and skillful doctor, and the Dhamma to proper medicine. However efficient the doctor or wonderful the medicine may be, the patients cannot be cured unless they take the medicine properly. So the practice of the Dhamma is the only way to attain the final deliverance of Nibbāna. These teachings ranged from understanding karma (Pāli: kamma) (literal meaning 'action')) and developing good impressions in one's mind, to reach full enlightenment by recognizing the nature of mind.