In the 8th chapter the old rebbe says that even one who did not know that the food is forbidden to eat, and ate it in order to serve G-d, the light in the food does not get included in the holiness, since it is forbidden. However if one ate something permitted, but not for the sake of G-d, even though it is now bad, it could still go back to be good if he returns back to serve G-d. However a trace of it stays in the body since it became a part of him, and therefore the worms consume the body after ones passing, in order to clean the body from what it ate not for the sake of G-d, and then nothing is left over from it. Unless he never had pleasure from this world as 'Rabbi Yehuda Hanassi ('Rabbi Judah the leader' the one who composed the 'Mishnah') which it is said about him that he never had pleasure from this world, rather everything he did was for G-d. Now the old rebbe explains different punishments for different things: if one speaks something which is not good and not bad and it is not possible for him to learn Torah, his punishment is that his soul cannot go into paradise or to the Gahanna. But if he speaks things which are forbidden as gossip etc. the punishment is to go to the Gahanna. And if one can learn Torah but still speaks things which have no purpose, his punishment is very severe and the old rebbe did not want to write it. But if one can learn Torah but still learns the wisdom of other nations and secular studies, it is even worse than just loquacity, since by loquacity he uses only his feelings which are seven powers, since every fool can speak like that, but by secular studies he also uses his three other powers of his brain. Unless he learns secular studies in order to be able to support his family so he can serve G-d properly, or if he can use it for the Torah.