The writings may be divided with reference to the two periods of Tertullian's Christian activity, the mainstream and the Montanist (cf. Harnack, ii.262 sqq.), or according to their subject matter. The object of the former mode of division is to show, if possible, the change of views Tertullian's mind underwent. Following the latter mode, which is of a more practical interest, the writings fall into two groups. Apologetic and polemic writings, like "Apologeticus", "De testimonio animae", the anti-Jewish "", "Adv. Marcionem", "Adv. Praxeam", "Adv. Hermogenem", "De praescriptione hereticorum", and "Scorpiace" were written to counteract Gnosticism and other religious or philosophical doctrines. The other group consists of practical and disciplinary writings, e.g., "De monogamia", "Ad uxorem", "De virginibus velandis", "De cultu feminarum", "De patientia", "De pudicitia", "De oratione", and "Ad martyras".