Dr Sarvapalli Radhakrishnan writes on Swamiji :
In any living culture, you will always find a perpetual process of renewal. What happens to be heresy today becomes heritage tomorrow. What is adventure for us today becomes legacy tomorrow. In other words, if a culture is to perpetuate itself, it is reaffirming its fundamentals and trying to readjust them to the requirements of each generation. If we lose this quality of self-renewal, the culture itself becomes decadent, It has been our good fortune that so far as the Indian culture is concerned, it has had this living vitality, this capacity to renew itself, to shed away the old and reincarnate itself in the new. In chapter 4 of the Bhagavad Glta, the Teacher says: 'I taught this yoga to Vivaswan, Vivaswan taught it to Manu. Manu taught it to Ikshvaku. Today I am teaching it to you, Arjuna.' In other words it is the same old Puratana Dharma also called Sanatana Dharma, the ancient doctrine. It is the eternal doctrine, that is being expressed in different ages by different individuals. The Buddha when he came said, 'I am the restorer of the ancient path. I am not giving you anything new'. Jesus proclaimed that he came to fulfil, not to destroy. In other words, all the great teachers of the world take up the fundamental truth, discard the excrescences, the accretions which had crept into them and recapture the original purity, and present it to their generation. The great teachers are the vehicles of the living Word. They are the voice of the inspired Logos. They are the people who give utterance to the Eternal, dwelling in each individual. They have the capacity to give articulate expression to them. Swami Vivekananda was a spokesman of this divine Logos and he took hold of the requirements of this age in which he was born and presented it so as to make a fervent appeal to the hungry heart and the searching mind of his generation.
He was born in an age when science was predominant. He was a student in a Calcutta college where he read the great works of Herbert Spencer, John Stuart Mill, Bentham, Thomas Henry Huxley etc. He was steeped in the spirit of science. He was restless in spirit. His mind tossed about hither and thither. He did not know what to do, became an agnostic, joined the Brahmo Samaj, gave it up and was in a pathetic condition of mind. He needed something to live by and he was not able to get that thing. He wanted to know whether there was anyone in this world who could catch the spirit, who could convince him that he saw God, even as we see the walls before us or the audience here. He wanted someone who cared for facts. Science is a study of facts. It is a study of actual experience and if one is to be satisfied by the spirit of science, he must feel that there is a Divine Reality which is a fact which has been sensed, tested and experienced by people. Chance as some people would call it, providence as others would say, led him to the door of Sri Ramakrishna Paramahamsa. He went to him in dire distress and asked him, 'Have you seen God? Can you prove God to me?' The answer came.: 'Yes. I have seen God. I have seen Him much more intensely than I see you here.' That was the man who was able to transmit to him, to communicate to him and to tell him that he saw the Divine Reality even as we see tables and chairs. Then the conversion happened. It was a moment of his rebirth, so to say. He became convinced of the reality of God. He said religion is not a matter of doctrinal conformity or ritualistic piety. They may be essential for people to reach a particular goal, but its fundamental reality is the sight of God. Faith must be replaced by sight. Blessed are the pure in heart for they shall see God. It is that seeing of God that makes a man truly religious. An authentically religious man is one who does not report from hearsay, who does not quote scriptures or authorities but says 'I have felt in the pulse of my being the reality of the divine. If there is one fact in this world, it is the supreme fact of God. As you have seen other facts I have noted this particu1ar fact. This is something which is vital to me, in which I live.'