Kirchhoff's law of thermal radiation rarefied material such as air, or transparent material, through which observations can be made. The interface is not a material body and can neither emit nor absorb. It is a mathematical surface belonging jointly to the two media that touch it. It is the site of refraction of radiation that penetrates it and of reflection of radiation that does not. As such it obeys the Helmholtz reciprocity principle. The opaque body is considered to have a material interior that absorbs all and scatters or transmits none of the radiation that reaches it through refraction at the interface. In this sense
A Tale of a Tub in the reception of Swift's work is that the narrator of the work is an extremist in every direction. Consequently, he can no more construct a sound allegory than he can finish his digressions without losing control (eventually confessing that he is insane). For a Church of England reader, the allegory of the brothers provides small comfort. Martin has a corrupted faith, one full of holes and still with ornaments on it. His only virtue is that he avoids the excesses of his brothers, but the original faith is lost to him. Readers of the "Tale" have picked up on