The meditator ascends the nine stages of meditative concentration (serenity, shamatha) by recognizing the two essential features of concentration, recognizing the obstacles that impede it, and applying the antidotes.  At this stage of the course, students begin a new practice: concentration combined with visualization, and learn how to recognize:  Distinguishing Features of Concentration:  vivid intensity, intense mental clarity  stability, one-pointedness  Faults That Prevent Serenity:  Laziness  Forgetting the instructions  Not recognizing agitation and dullness  Not applying antidotes  Over-applying antidotes