NUM183 The factors that undermine th[e] virtue [of piety] are [the result of] insufficient examination in the aforementioned matters, i.e., the lack of awareness regarding the base nature of pleasure, the pursuit of honor, and insufficient preparation for the service of the Eternal. The first two factors sway a person's thinking, lowering him toward other motives, like an adulteress who consorts unfaithfully with other men. These externally oriented motives are called "the adultery of the heart," as it is written [this verse]: "And you must not be searching, following your heart and your eyes after which you [tend to] stray." For the tendency of the heart is to stray from the ideal perspective that it was meant to cleave to, [embracing instead] vanities and false appearances. And [the latter factor] – preparing oneself insufficiently – prevents the removal of one's heart of that innate thoughtlessness that derives from the material world. This thoughtlessness befouls the Divine service with its stench.