Leonardo’s remark suggests that unwanted behaviour, impulses or problems are usually easier to stop before they become established. At the beginning, a person may still have greater freedom to choose a different course. Once a pattern has developed, repetition, attachment or accumulated consequences can make resistance more difficult.

The statement can be understood as a general observation about self-control and prevention. Small decisions may become habits, while minor problems can grow if they are repeatedly ignored. Acting early therefore reduces the effort that may later be required to change direction or repair the consequences.

The quote does not imply that change becomes impossible once a pattern is established. Rather, it stresses the practical advantage of recognising difficulties at an early stage. It can apply to personal habits, conflicts, commitments and other situations in which delay allows momentum to build.

Alternative translation

“It is easier to contend with evil at the first than at the last.”