What is the role of Rishis like Vasishtha in the Hindu philosophy?

Answer 1

Hinduism is a way of living according to one's understanding of principles of the Vedas and the Upanishads. The Vedas are revealed knowledge. Just as the knowledge of gravity was revealed to Newton, similarly, in India, many Rishis or Seers were awakened to certain transcendental Eternal Truths. These Rishis realized that their real nature was not concerned with or linked with 'body or mind', nor was it dependent on sense perceptions, but was in fact Divine and identical with Universal Consciousness.

The Upanishads

These Seers realized their oneness with all beings, and even identified themselves with Transcendental Truth beyond all beings. The state of altered consciousness in which the Seers become one with Truth is spoken of as Samadhi. The Self-realized Seers termed this Reality as Atman, Brahman, Pure Consciousness, or Supreme Being. In course of time, the word God was also interchangeably used with Brahman or Atman.

This state of being one with Brahman or Atman was transient but very intense, and many a person gave up his or her body in this blissful state. Thus, their experiences were buried or cremated with them.
Fortunately, a few Seers could come back from the state of Transcendental Consciousness to human consciousness, and they were able to express, albeit sketchily, their experiences of that state. They, and their disciples, tried to describe the state that was beyond words and speech. Therefore, their words were inadequate to give full account of the nature of those experiences and of the Truth. The Upanishads contain closest possible approximation of such transcendental states in the language full of poetic richness, similes, and metaphors. But as the Seers lived in different time, culture, and place, the text describing their experiences appeared different.

However, one thing was certain and common: That the state they experienced or realized was full of Bliss, beyond comparison with any pleasure or joy obtained by one or all the five senses. It was much higher than sensuality of sex, much enthralling than the sweetness of music, more beautiful than any scenery experienced by the eyes, or any taste perceived by the tongue. Secondly, these Seers felt, out of compassion and love, that everyone should experience such a wonderful and unique state. They were also sure that every being is potentially capable of reaching there, because it was the inner and real nature of all!

The Yoga and Rituals

These rishis, accordingly, prescribed certain methods and practices for various persons according to their aptitude and spiritual development. They felt that certain people were almost ready to get the taste of Bliss. They called them 'adhikari', i.e. having ability and qualifications to undertake and fulfill the ardent spiritual disciplines required to realize the Transcendental Reality. Others needed some more time, for their attachment to worldly concerns and senses was intense. And therefore, these people needed or required to undertake certain sacrifices before they became fit for realization of the highest knowledge. Thus, Yagna (sacrifices) came into existence. From birth to death, in the ceremonies of marriage and childbirth, on every family and social occasion, certain rituals were laid down that helped in imparting certain measure of self-sacrifice (detachment from bodily pleasures) and control of senses....

Answer 2

Factually I cannot add to Copy&Paste, but for another biological perspective, I suggest you read J. Chilton Pearce's "The Biology of Transcendence."

It is my experience and opinion that Rishi 'realization' is not relevant to the lives of most "seekers" - only a rarefied few - because it tends to disconnect one (literally) from this plane of reality and our purpose for coming here. This is a factor to keep in mind when exploring Hindu philosophy which is rich in metaphorical symbolism and wisdom, but I have found less practical in its application in this dimension, global culture and time.

Answer 3

This depends on the perspective of the student