Arjuna accepted Kṛṣṇa as teacher; therefore He is chastising him that, "You are talking like a learned man, but you are lamenting on this body. But no learned man laments on this body, either dead or alive." Because without the knowledge of the active principle which is moving the body, what is the use of simply understanding the bodily construction? The medical science knows the construction of the body, anatomy, physiology, the bone, this muscle, the blood and everything, but he does not know what is the active principle. When the active principle gone, they cannot repair it.
So there may be vast advancement of medical science, but if the medical science cannot check birth, death, old age and disease, then what is the use of it? It may have some temporary use, but actually it is not science. Nobody wants to die. Is there medical science which can stop death? So that knowledge may be temporary, beneficial, but ultimately, it is not the knowledge. I am anxious for not dying. Nobody wants to die. This is my anxiety. And where is that science, medical science? So we are satisfied with some temporary knowledge. We have no ultimate knowledge. And because it is very difficult subject matter, we have avoided it very carefully.