The cultivation of Calm (`samatha-bhaavanaa) aims at perfect steadiness of the reflected image (pratibimba) in thought (citta) of the meditative object (aalambana). Success is constituted by the ninth (and last) thought-fixation (citta-sthiti) which is the only mental orientation driving without effort (anaabhogavaahana-manaskaara), due to previous, but no longer required, eliminative activation (prahaa.na-sa^mskaara), i.e., activations eliminative of meditative faults in the first eight thought-fixations. Thus, the ninth thought-fixation is carried by habituation (svarasavaahita) accomplished in the eighth thought-fixation, which still had effort. This is equivalent to the svarasika ("purely passive") of Stcherbatsky in this passage:
It [the unexpressible reality] is the pure object, the object cognized by the senses in a pure sensation, that is to say, in a sensation which is purely passive, which is different in kind from the spontaneity of the intellect.
The meditative object of Calm alone is called Reflected image devoid of discernment (nirvikalpa-pratibimba); that of Higher Vision alone is called Reflected image attended with discernment (savikalpa-pratibimba). The meditative object of combined Calm and Higher Vision (`samatha-vipa`syanaayuganaddha) is called Fulfillment of the requirement (kaarya-parini.spatti).
http://ccbs.ntu.edu.tw/FULLTEXT/JR-PHIL/alex6.htm