Some personalities have such impact that their effect is seen thousands of years after their lifetime.
Yajnavalkya is one such immense personality, a rishi from ancient India who lived somewhere between 800 to 700 BCE. He thus preceded the Buddha by around 300 years.
Although not much is known of his life, his impact is seen more from his works.
He is responsible for several texts and many of the Vedic portions of the Shukla Yajurveda were revealed to him. He is credited with being one of the earliest expounders of Advaita Vedanta.
He is said to have authored many texts, including the Isha Upanishad, the Brihadaranyaka Upanishad, the Yajnavalkya Smriti, Shatapata Brahmana among others.
Human beings experience the world through the sense organs. This occurs both in the waking and the dream states.
One then assigns names and forms to the objects of the senses.
It can be safely said that names and forms account for all of human experience. Consciousness appears to be the common factor underlying this entire experience.
The final means of knowledge in ancient Indian philosophy is the experience of truth. “Enlightenment”, however one may define it, is said to be achieved via Jivanmukti (liberation while one is alive).
The idea of consciousness is not fully understood today by human beings. One of the reasons could be that we are using the very tool to study itself. Kant posited that human beings can only interpret sense data using an apriori structure. Since the 1960s, research in artificial intelligence has revealed that an embodiment is a requirement for any level of intelligence to work in, say, a robot. It appears that humans have been pondering about consciousness for a long long time.
There is an ancient Indian idea about the nature of ultimate reality In Sanskrit, it is called brahman. There is a school of thought which states that this ultimate reality is formless and without attributes. This school is called the advaita or nondual school. There is another school known as the samkhya school, who are strict dualists and posit the existence of two entities: a primordial nature (prakriti) and a consciousness (purusha) which gives life to this nature.
It is interesting to think about the idea of consciousness taking into account the modern research in combination with the above and other ancient ideas.