Burns are classified by depth as first, second, and third degree. First and second degree burns are limited to the outer layer of human skin, the epidermis. First-degree burns cause redness and pain (e.g., sunburn). Second-degree burns are more painful and marked by blisters (e.g., scald by hot liquid). In third-degree burns, how ever both the epidermis and dermis are both destroyed, and underlying tissue may also be damaged. When a burn is that deep a victim will not feel any more pain because the nerve endings, pain receptors, which are located in the upper part of the dermis layer are completely destroyed.

In the verse mentioned above God says:"as often as their skins are roasted through We shall change them for fresh skins". He doesn't stop there but He continues to explains why he does that "that they may taste the penalty".