[373] Purity of the mode of practice (paṭipadāvisuddhi) is the beginning of the first jhāna. How many characteristics does the beginning have?
The beginning has three characteristics: the mind (citta) is purified from whatever is an obstacle (paripantha) to it; because it is purified, the mind enters upon the intermediate sign of serenity (samathanimitta); because it has entered upon it, the mind leaps forward therein. In that the mind is purified from the obstacle, in that, because it is purified, the mind enters upon the intermediate sign of serenity, and in that, because it has entered upon it, the mind leaps forward therein — purity of the mode of practice is the beginning of the first jhāna; these are the three characteristics of the beginning. Therefore it is said that the first jhāna is both beautiful in the beginning and endowed with the characteristics.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.