This small work is aimed towards all those who possess interest in ancient Indian wisdom. An attempt to re-arrange and cirtically analyze the material related to human physiology available in classical Ayurvedic textbooks has been made here. Original verses have been given in Devanagari script along with their gist, which is followed by author's comments in English. These comments are based on the contemporary medical physiology. Understanding the Ayurvedic explanations in terms of contemporary medical physiology becomes essential for an Ayurvedic student because dependence on modern medical science is obvious in day-to-day clinical practice. This is especially true as far as modern diagnostics methods are concerned. If a physician is going through the laboratory report of a patient with liver disease for example, he or she should be aware of the fact that the functioning of 'Bhutagni's is impaired and is being assessed. Similarly in hormonal abnormalities the 'Dhatvagni's are probably abnormal. Therefore, it is hoped that this book will prove helpful for all Ayurvedic students pursuing their undergraduate or postgraduate studies.