A mitzvah draws along another mitzvah, and a sin draws along another sin. (Ethics of the Fathers 4:2)
One day I received a panicky call from an alcoholic patient whom I had treated several years earlier. He had been at a gathering at a friend’s home, and although he had specified that he wanted a soft drink, his first sip told him that there was alcohol in the drink. He called me for instruction of what he might do, since he knew from past experience that one sip of alcohol sufficed to set in motion a chain reaction that would end in a drunken stupor. He stated that he was prepared to admit himself into a hospital if necessary in order to prevent this brief exposure to alcohol from escalating into a full relapse. Although he had only consumed a small amount and had done so purely accidentally, his fear was legitimate.
Let us suppose that a family which is meticulously observant of kosher laws discovers that a particular product that they ate under the assumption that it was kosher had lost its hechsher (rabbinical approval) because a non-kosher ingredient had been added. Although they certainly would regret having ingested something that was not fully kosher, they probably would not call their rabbi for instruction on how to prevent this accidental transgression from dragging them down to other forbidden types of behavior. This mistake may be more serious than their original error.
Doing wrong, even inadvertently, renders us highly vulnerable to further transgressions. Remedial measures, i.e. prompt teshuvah and an effort to do better in the future, must be undertaken to avoid deterioration.