The Hindu religious tradition is unique among the world's traditions in that it admits of two categories of Scriptures: the timeless and the time-bound.

Those scriptures or those portions of scriptures that deal with the ultimate nature of the universe and reality are 'timeless' because the Highest Truths that Hinduism teaches never change. Whatever the nature of the flux and change outside, the deep inner spiritual truths of the soul and its relationship with the Gods and the universe remain the same, and these are the central Truths that Hinduism hinges upon. These are called the 'Shruti', literally meaning 'the heard' or what has been revealed in the depths of Samadhi by great sages of Hinduism. The Shrutis give authentic guidance in terms of the nature of Truth and the ways to attain it. The Four Vedas, the Upanishads (portions of the Vedas), the Brahma-sutras (a coherent ordering of the Truths presented in the Upanishads) and the Bhagavad-Gita are the primary Shruti.

Those scriptures that deal with humanity's socio-political settings and customs are said to be time-bound, as these are dependent on place and circumstance. As humankind continually evolves through different ages, the Truths contained in the Shruti have to be applied and interpreted appropriately. There cannot be one law for all time because what is good in one age may not be so in another. For instance, during the centuries of foreign invasions, Hindus had to go into a very protective way of living so that their values may be preserved. But upon regaining independence, these customs are now relaxing.

Such time-bound scriptures are called 'Smriti', literally meaning 'the recorded' or 'the remembered'. These are works by great teachers that serve as guidelines for conduct in everyday life. It must be emphasised here, that unlike other traditions Hinduism differs here too, in that not even the Smriti is a strict 'dos and don'ts' code like, for instance, the Ten Commandants. Rather the Smriti only suggest to people as to what constitutes righteous behaviour. The Purana (Bhagavata purana, Vishnu purana, Siva purana etc), Itihasa (Ramayana, Mahabharata etc), the Dharma Sutra (of sages Apastambha, Gautama, Vasishta etc), and the various codes of conduct based on these (of Manu, Yajnavalka, Sanakara, Parasara etc) are the main Smritis.

Based on the timeless spiritual values enshrined in the Shruti texts, like universal love, harmony and wisdom, the Hindu thinkers contemplate their ideal application on contemporary life and hence arrive upon the new Smriti required for each new age. This constitutes the Dharma of the age and continuously evolves with time. Thus 'religious reform' as spoken of from an Abrahamic (Monotheist) point of view just doesn't apply to Hinduism which is based upon the idea of a dynamic Wheel of Law (Dharma-chakra) having the Sanatana Dharma for its fulcrum.