Concentration of difficult progress and swift direct-knowledge (Buddhism)

Cultivating what is unsuitable, failing to carry out preparatory tasks, overwhelmed by craving, lacking practice in serenity (absorption concentration), having an acutely corrupt nature, all these mean progress is difficult. Cultivating what is suitable, having skill in absorption, not overwhelmed by ignorance, having practice in insight, having keen faculties, all these mean intuition is swift.

According to Hinayana Buddhism, concentration is considered as of one kind (monad), of two kinds (dyads), of three kinds (triads), of four kinds (tetrads) or of five kinds (pentad). In the first tetrad, this is the second concentration.