Sanatana Dharma was most appropriately so named for various reasons. The first word Sanatana is easy enough to translate; and it means Eternal; but the second word Dharma is difficult to translate into English, because there is absolutely no word which can correctly convey, in English, what the word Dharma means to us in Sanskrit and all the various languages of India.
It may be roughly translated as "Religion" but this is really a very unsatisfactory rendering thereof, because the very conception which the Western mind has of Religion is something very narrow and restricted in its nature and scope.
It is not all-comprehending as our Sanatana Dharma is, in the sense that it pervades and, permeates every activity of ours in every branch and department of life, not merely from our birth to our death but commencing long before our birth and continuing its rule over us for long ages after our death.
Thus, as regards the various departments of life and knowledge coming under the jurisdiction of Dharma according to the scriptures, the very conception thereof is absolutely foreign, nay, apparently even impossible, to the followers of these other religions.
To them, Dharma is something of an intensely narrow, cramped, cabined, restricted and circumscribed character; and this is why there is no word in English for correctly translating all that the word Dharma means to us.
Our Sanatana Dharma defines Dharma as that which prevents us from going down, running ourselves in any manner or respect whatsoever, and makes for our welfare, progress and uplift all-round.
It is not something very small and circumscribed (like "Religion" it the Western sense of the word) but really and thoroughly all-comprehending, as it knows no limitations of any kind whatsoever.
For example, besides the fact that our Vedas themselves deal not merely with the means required for the attainment of happiness and joy in a future world, but also prescribe the necessary means for securing of happiness on the physical, material and other so-called purely "secular" planes of life.
There is also the eloquent fact that the very names of our four Upavedas, i.e. Ayurveda (which includes anatomy, physiology, medical and sanitary science and surgery), Dhanurveda (including archery and other military sciences), Gandharvaveda (including the science and art of music) and Sthapatyaveda (architecture, engineering, sculpture, drawing and painting) will suffice to show wide is the range of Sanatana Dharma's jurisdiction.
Similarly, the inclusion-within the Vedangas-of grammar, prosody, lexicography, astrology based on astronomy. And other such departments of what the modern western world would call purely "secular" knowledge, will also clearly show and conclusively prove this very same unique feature of Sanatana Dharma.
It needs no elaborate pointing out that it seems almost impossible even to conceive of the western world ever recognizing the study of Grammar, Prosody, Lexicograhpy, Astronomy and other such "purely secular" departments of knowledge as necessary and inherent parts of religious study.
But our Sanatana Vaidika Dharma includes, within its all-comprehending jurisdiction, all departments of knowledge (including all branches of what, in modern terminology, we speak of as the positive sciences).
It is, therefore, in the fitness of things, that our Sanatana Dharma, which has not merely existed from the time of Creation, but has to and does cater for all kinds of adhikaris, has naturally made all the necessary provision for all the different activities of life, by going into detailed disquisitions on all the varied requirements thereof, and setting forth an all-embracing and through-going system of injunctions and prohibitions, correct and faithful adhesion whereto is not only intensely and extremely useful but also positively and absolutely necessary of the attainment by us of all-around health, strength, peace, happiness and joy (of body, mind and sprit).
Undoubtedly, it is this very fact that is responsible for the intensely wonderful and immensely gratifying confirmation which the precepts of our Sanatana Dharma have been systematically receiving of late-on intrinsic merits-from Modern Science in all its multifarious branches.
It is clear, therefore, that the Sanatana Vaidika system was based, not merely in its general plan and outlook but also in every one of its details, on a thorough-going and scientific basis of the most unexceptionable and far-reaching character which took into account all the various phases and aspects of life (physical, material, mental, intellectual, moral, political, industrial, economic, psychic, spiritual and so forth).
Excerpted from Dialogues with the Guru