Sri Ramakrishna was one of the greatest mystics and sages of modern-day India, and one of the greatest synthesizers of the mystical traditions of all the great world-religions. He was born in a small village called Kamarpukur, near Calcutta, on February 18, 1836, and from a very young age exhibited strange behaviour and a tendency to pass into trance states. One of the most retold incidents involves him walking through a field one day and seeing a flock of birds pass overhead - overcome by the beauty of the scene, he passed out. These kinds of things were always happening to him. He would be talking to someone or performing some task in school, and he would suddenly freeze, his eyes would unfocus, and he would stop responding to anything around him.
People were able to dismiss this kind of behaviour as childhood eccentricity, or sometimes illness, but when Ramakrishna became a teenager it was more and more obvious that he had a religious and mystical calling. He started to spend hours in the temple worshipping at the feet of the statue of Kali, the mother-goddess of death and destruction, who was depicted as a black-skinned woman with a lolling red tongue, her hands holding weapons and the heads of men. Kali is often misunderstood by Westerners, who see her as a dark and forbidding icon, and the Thuggee death cult has definitely not helped that reputation, but Ramakrishna had a deep understanding of Kali as the necessary force of renewal and change that pushes all life onwards. He claimed to have a direct relationship with Kali, and to talk to her every day. He became a priest in the temple of Kali in Dakshineswar, and his devotions started to worry his family so much that they decided he was insane, and moved him back to his home village and made him marry a young girl called Sarada. However, they couldn't stop him from returning to the temple, where he continued to see visions and talk to the goddess loudly, often in front of the entire temple congregation.
It was only after he began to encounter highly developed spiritual teachers that his true nature began to emerge, and people stopped thinking he was crazy. Two academic theologians visited him to 'assess' him, and decided that the boy was an avatar - a living manifestation of the Divine being, greater than any mere human mystic. Ramakrishna's response was "Well, I'm
glad it's not a disease... But believe me, I know nothing about it.". Next he met a tantric nun who was visiting his village in 1861, and she instructed him in various tantric practices (note: tantric practices can be sexual, but not necessarily. In this case, Ramakrishna is said to have remained celibate throughout his life, which must have been plenty of fun for his wife). Another teacher found him a couple of years later, Tota Puri, a master of Advaita Vedanta, the Vedic practice of mental discrimination between reality and unreality. The practice of Advaita is supposed to lead to a state of formless, contentless consciousness, devoid of any objects or identification whatsoever - nirvikalpa samadhi. The story goes that Ramakrishna progressed with enormous speed through his teacher's exercises, but found it terribly difficult to pass the final barrier - renouncing the image of his beloved Kali, the mother goddess. Every time he would come to the threshhold of samadhi, the image of the great Mother would appear to him, and he was unable to use the Advaitic practice to deny her reality. Tota Puri knew what Ramakrishna's potential was, and with great urgency he told him to try again, and this time he pushed the point of a shard of glass into Ramakrishna's brow, between the eyes, saying "Concentrate here!", after which Ramakrishna entered samadhi and remained motionless in bliss for 3 days.
In fact, this became another problem for him. Instead of dancing in front of the temple durga, he wanted to spend all his time immersed in the samadhi trance of pure consciousness. He decided that he was going to relinquish his physical life, and remain in samadhi until he died, and sat down by a river some ways away from where he lived in order to do this. A wandering sadhu found him after a week or two, and realized immediately what he was doing, and decided that this person was too valuable to die. After trying to snap him out of his trance without success, he decided to stay and look after Ramakrishna's physical needs for as long as it took to return him to waking consciousness. After a long period (my source said six months, but this is undoubtedly exaggerated), during which the monk washed him and forced small amounts of food and milk down his throat, Ramakrishna returned to full awareness, having had a vision in which Kali appeared to him and told him that it would be selfish of him to remain in samadhi, because he had work to do in the world.
After this, Ramakrishna began the spiritual work for which he is most famous - he took up the practices of several other religions, following them earnestly and to their conclusions - most importantly, he practiced Sufi Islam and Christianity, attaining the highest mystical experiences of these paths. After these experiences, he began to teach, proclaiming as his message that all religions and mystical paths were one and the same, though their symbols and language were different. He used to express this truth in many ways, but perhaps his most succinct was "Cake tastes nice whichever way you eat it." He waited for a long time without any devotees, and his hunger to teach was so intense that he would sometimes climb to the roof of the temple and wail for his followers to come, wherever they were. Eventually, beginning in 1879, they started to arrive, and he worked quickly to build up a core group of serious and advanced pupils, aware that he probably did not have much time left due to the immense hardship through which he had put his body during his life. In traditional Hindu teaching, it is said that a human being cannot withstand being in the state of samadhi for more than a few weeks without dying, and Ramakrishna had been entering this state every day, several times a day, for his entire life. In fact, sometimes he literally had to hit himself on the top of the head to try and make himself stay grounded in the physical realm.
His method of teaching was not based on mental agility or words - he always spoke in extremely simple terms about God and reality and realization, with a slight stammer and in a dense country dialect, and told people not to feel that they must follow any particular path or goal. Instead, he said, they must learn to see the Divine manifesting in every person, and in themselves. He would punctuate his talks with demonstrations of what he was saying, passing into trances and Yogic poses spontaneously. There is a famous photograph of Ramakrishna with his devotees in which he is standing in their midst, smiling broadly, his hands and arms raised in Yogic mudras. There is also someone behind him holding him up so that he doesn't simply fall over, like a statue. The photograph can be found here: http://www.vedanta.org/photos/pages/R/ramakrishna.html (no.R3). Things like this were always happening him, all his life - he had to be accompanied constantly, as he was liable to pass into samadhi at the smallest provocation, and, if he was walking, fall over and hurt himself. Once he dislocated his shoulder in this way. Life with him as his student was very strange, and also amazing - Ramakrishna was constantly in a state of ecstasy - crying, laughing, singing and dancing, and involving everyone around him in his madness, trying to get them to feel what he did - the constant presence and reality of God.
His most favoured student was called Narendra, and Ramakrishna claimed that he was the reincarnation of a very great sage, who had come into this life specifically to help Ramakrishna with his work in the world. He named him Swami Vivekananda, and he eventually became the first great Hindu mystic to bring the Eastern teachings to America at the first Parliament of Religions in Chicago in 1893. Ramakrishna himself died in 1886 of throat cancer, all the time cheerfully telling his devotees to stop being so sad, because it was only his body that was dying. At the end, he shouted Kali's name three times and passed into samadhi for the last time - mahasamadhi, the passing on of a great mystic into the other world. Vivekananda kept his promise to bring Ramakrishna's message to the world, and he was followed by Ramakrishna's wife Sarada, who attained a high level of realization and became known as Sarada Devi. Today there are millions of people around the world who he has influenced to variuos degrees - devotees, theologians, religious synthesists, peacemakers, or even just ordinary people who have read about him and become fascinated by his life. Even if you don't have the kind of personality that can venerate another human being in a religious sense, you can still be amazed at the way in which Ramakrishna lived - the joy and intensity and strangeness with which he did everything, and the happiness of his message of unity, so incongruous and necessary, since religious difference has been, and continues to be, the number one excuse for people all around the world to kill each other.
References and further reading:
http://www.geocities.com/denali_higdon/Drama.html
http://www.softcom.net/users/vedanta-sacto/rkbiofr.htm
http://www.ramakrishna.org/rmk.htm
http://www.sriramakrishna.org/rkmhist.htm
http://www.vedanta.org/ramak/ramak.html