Dasa-müla-tattva

Srila Bhaktivinode Thäkura
The nature of sädhana-bhakti
krti-sädhyä bhavet sädhya-bhävä sä sädhanäbhidhä
nitya-siddhasya bhävasya präkaöyaà hådi sädhyatä
"When the senses are engaged to attain the ultimate goal of spontaneous devotional surrender, this is known as sädhana bhakti. The pure devotional tendency of the jéva is eternal and self-perfected. However, the process by which this latent attitude is awakened is sädhana, practical devotional service guided by scriptural injunctions."
The real point is that any effective conducive method to direct and repose the consciousness in Kåñëa continuously is, in fact, sädhana-bhakti—also known as upäya-bhakti. This sädhana-bhakti is of two types: (1) vaidhi, regulative devotion adhering to scriptural rules and (2) rägänuga, regulative devotion inspired by spontaneity of the heart without overt compliance to rules. Vaidhi-bhakti is symptomised by a quality of devotion that is solely ruled by scriptural injunctions, curbing the natural flow of attraction and taste for Çré Kåñëa. The regulative principles of vaidhi-bhakti are enjoined in the scriptures to be followed by all the four social and religious orders of the varëäçrama system of society—brähmaëa, kñatriya, vaiçya, çüdra and brahmacäré, gåhastha, vänaprastha, sannyäsa.
We find a quote from the Närada-païcarätra cited in Bhakti-rasämåta-sindhu (Brs.Pur. 2.8):
suraåñe vihitä çästre harim uddiçya yä kriyä
saiva bhaktir iti proktä tayä bhaktiù parä bhavet
"All activities recommended in the scriptures are to be performed for the Supreme Lord Hari. This is called sädhana-bhakti or upäya-bhakti. By this process one can attain parä bhakti, also known as sädhya bhakti."