Why Is the Manas Easily Contaminated during Sitting Meditation?

Why is it that when sitting in meditation, one can more easily think things through and understand, and the manas is more easily influenced and perfumed? Because when sitting in meditation, the mind consciousness becomes still and no longer engages in wandering thoughts; non-valid cognition and inference rarely arise in its discrimination, and direct perception predominates. In this way, the manas is easily perfumed, and the mind consciousness can also lead the manas to deliberate on the Dharma principles together, making it easier to comprehend the principles, and understanding comes quickly.