In plain words
We must try to understand well the vision of the ṛṣis of that age, and how lofty the intelligence of humanity grew to be. What does Īśa mean? Splendour, wealth, fame, renown, Jñāna and Vairāgya. They said that Īśa is the very embodiment of the six forms of wealth. To the principle that Īśvara is the embodiment of these six forms of wealth, they went on giving the name Īśa.
After that the human mind and intelligence went on growing day by day. At the last they called Him Aprameyaḥ. What does Aprameya mean? The One whom no measure can grasp. We can go to the ocean and measure it with a tape. We can even measure the sky. But there is no measuring rod at all with which to measure God. God is beyond the three means of knowing: direct perception, inference and the word of scripture. Because He is beyond these three means of knowing, they called Him Aprameya. God, the Immeasurable, pervades everything everywhere. If there were no such principle of God, there would be no world at all. Whether a human being believes or does not believe, this divine power pervades everywhere and goes on shining. Many ṛṣis went on doing tapas, longing to recognise such a God directly. They came to recognise that the supreme goal and the very end of our life is to recognise the Divinity that is its basis.
Some kept trying and trying, grew weary and gave up, saying, this is a task beyond us. Others gave up at the very start, saying, where is humanity and where is Divinity, there is no link at all between the one and the other, so it is impossible to recognise what lies beyond such a thing. No, no. This sacred human life has come from that very Divinity. Mamaivāṃśo jīvaloke jīvabhūtaḥ sanātanaḥ. Humanity is that divine part itself. It is vital for the son to recognise his father. So some ṛṣis held to the vow that they must never let go, however many troubles arose and whatever obstacles of every kind came, and went on striving. At the last, through that divine power, they were able to recognise Him. The ṛṣis who had recognised Him did not keep it within themselves alone; they went on proclaiming it to the world. Uttiṣṭhata jāgrata prāpya varān nibodhata. O human beings, living in the sleep called ignorance!