Why Does One Waver in Doubt?

Once the manas accepts a certain principle, at any time it will be resolute and decisive, without hesitation; whereas whatever comes from the mind consciousness's deliberation (manana) is invariably tinged with doubt, hesitation, and back-and-forth wavering. It is like riding a bicycle: being able to ride and believing one can ride are two completely different states of mind—the former is without hesitation, while in the latter the mind cannot be fully certain. Some people harbor doubt within but are unaware of it, thinking they have no doubts; that is because their minds are too coarse, their power of introspection is weak, and their meditative concentration (samādhi) is insufficient. Therefore, when one does not see the truth, one will deceive oneself.