1. At the beginning of the night of the fourteenth of Nissan we search for chametz (leavened food) by the light of a candle. This inspection must include searching in all holes and crevices – any place where chametz is brought during the year (Shulchan Aruch and Mishnah Berurah 431).
2. On the Scriptural level it is sufficient to either “nullify” whatever chametz one owns [by declaring it void and ownerless] or search for and destroy one’s chametz. However, the Sages instituted that we do both methods. They did not rely only on the searching and destroying of the chametzlest an individual not search properly and he would thus own chametz during Pesach. They also did not wish to rely on nullification for fear that an individual who owns a large amount of chametz would not really intend on nullifying it. Plus, if one would rely only on nullification – even if it was truly nullified – perhaps the person will see it during Pesach and will come to eat it (ibid.).
