SADHANA is that which produces siddhi. It is the means, or practice, by which the desired end may be attained, and consists in the exercise and training of the body and psychic faculties, upon the gradual perfection of which siddhi follows; the nature and degree of which, again, depends upon the progress made towards the realization of the atma, whose veiling vesture the body is.
The means employed are various, such as worship (puja), exterior or mental; sastric learning ; austerities (tapas); the panca-tattva, mantra and so forth. Sadhana takes on a special character, according to the end sought. Thus, sadhana for brahma-jnana, which consists in the acquisition of internal control (sama) over buddhi, manas, and ahamkara; external control (dama) over the ten indriyas, discrimination between the transitory and the eternal, and renunciation both of the world and heaven (svarga), is obviously different from that prescribed for, say, the purposes of the lower magic.
The sadhaka and sadhika are respectively the man and woman who perform sadhana, They are, according to their physical, mental, and moral qualities, divided into four classes – mrdu, madhya, adhimatraka, and the highest adhimatrama, who is qualified (adhikari) for all forms of yoga.
In a similar way the Kaula division of worshippers are divided into the prakrti, or common Kaula following viracara, addicted to ritual practice, and sadhana with Panca-tattva; the madhyamakaulika, or middling Kaula, accomplishing the same sadhana, but with a mind more turned towards meditation, knowledge, and samadhi; and the highest type of Kaula (kaulikottama), who having surpassed all ritualism meditates upon the Universal Self.