Why did the Chazon Ish slap his favorite nephew?

The great fear of the hurricane which threatens the United States, led some Jews from Lakewood to turn to R' Aharon Leib Steinman, and ask him in what area they should add chizuk due to the event.

R' Aharon Leib told them that "one has to strengthen Shmiras Shabbos, and especially on the subject of carrying on Shabbos." Hagry"l then expanded to explain that many times people carry through the city without checking if there is proper Eiruv, and one should carefully check the matter. Finally, Hagry"l took leave of them with a blessing that "no harm should befall any Jew".

R' Aharon Leib later told his family that his father Harav Noah Zvi z"l was appointed in the town of Brisk to examine the Eiruv, and would go around every Friday with a horse and cart around the city to see if the Eiruv is in order. And often they had to correct the Eiruv because of the "shkotzim", who would ruin the Eiruv on purpose, and even on Shabbos itself it could happen that they would spoil the Eiruv, and they had to call a goy who could climb the electric poles [with special shoes] to correct the Eiruv.

Since the Hamin (Cholent) of the city were placed in the oven of the local baker, when the Eiruv was broken they would ask a non-Jew to bring the cholent to their home.

Another story which R' Aharon Leib told, that he Rosh Yeshiva of Ponevez, Hagaon Harav Shlomo Berman zt"l asjed the Chazon Ish why when the Eiruv is torn in the middle of Shabbos it is not considered 'Misasek'. And why they go out to announce not to carry, for even if they carry it is only 'Misasek' with an Issur Derabonon. But the Chazon Ish did not answer the question of his nephew, and instead of an answer slapped him lightly on the cheek!

Members of the house of R' Aharon Leib asked him "What really is the answer to the question of HaGaon Harav Berman?" Replied R' Aharon Leib that "Misasek" is only where he lacks knowledge in the "cheftza" (the essence) of the matter, for example one who intended to take a detached vegetable and detached the connected and the like, but when the entire question is a "Chiluk Bedin" (difference in law) such a thing is not considered 'misasek'. And since the difference between Reshus Harabim (public domain) and Reshus Hayachid (private domain) is a chiluk bedin, and sometimes the difference is not even visible – one does not say of such a thing that he is "Misasek".

'בחדרי' גם ברשתות החברתיות - הצטרפו!