After the death of his mentor , Seyyid Burhaneddin, Mevlana took over his father's post as madrasa teacher , and began to teach a large group of students who gathered around him, and to preach to the people of Konya. His knowledge of the main 'madrasa' sciences of the time such as canonical jurisprudence, interpretation, tradition and theology was considerable, and he engaged in research into the philosophies of the leading Iranian, Indian and Arabic scholars of the day. He also knew Greek, and both read and interpreted the major classic philosophers. Before long, his madrasa became a centre of learning, attracting some of the leading philosophers of the day, such as Semseddin-i Mardini, Kadi Siraceddin-i Urmevi and Sadreddin-i Konevi. Mevlana himself, highly respected among a formidable body of learned men, continued both to address popular audiences in the mosque, and to train students at the madrasa for some time. He became a leading authority on matters of jurisprudence, and was generally regarded with awe by all sections of society it was at this time that his popular sermons were written down by his followers and inscribed in the seven part work entitled the Mecalis-i Seb'a.
Mevlana was also widely loved by his contemporaries as a philosopher and a person of extraordinary intellectual maturity. He was, however, dissatisfied with the extent of his knowledge and understanding, and began gradually to move towards a mystic approach to philosophy which was to contribute much to esoteric notions of devotion in its dynamism. Such was his passion for mysticism that it could, at anytime have come to the fore. He was no longer happy in Konya, but in its early stages, this aspect of his mysticism was unknown to his followers. It required an outlet, a means of expression, a way for him to embrace the universe, to proclaim the true mystic realities; it needed an impetus for this esoteric flame to burst forth.
On the 25th November , 1244, Mevlana left the madrasa as usual, tired and pensive at the end of the day. Mounting his ass, he made his way home, when suddenly the reins of his ass were grasped by a stranger who came face to face with him. The figure was that of a crazed and elderly itinerate dervish, dressed in rags, with beard and hair knotted, an unkempt creature who stood, however , steadfast before Mevlana. As Mevlana stared at the strange figure, he asked ''Are you not Celaleddin of Balkh?'' and on receiving the reply, he went on... ''Tell me...'' asking Mevlana several questions. The answers seemed to excite him greatly, as he grasped Mevlana's hands. This was the beginning of an extraordinary relationship between the dervish and Mevlana, who dismounted, taking the elderly man to his house. For days, even weeks, Mevlana did not return to the madrasa but remained with the dervish, deep in philosophical discussion. His new acquaintance was Semseddin of Tabriz.
According to mystic sources, Sems became a mystic at a tender age, and studied with a number of sheyhs. But unable to find the answers to his philosophical queries, he wandered from place to place, seeking out Sufis in every city he passed, searching for a guide to his spiritual ecstasy . Hearing at last of Mevlana Celaleddin, he was urged by an inner voice to go to Anatolia and meet the sage. Arriving in Konya he enquired after Mevlana at an inn, followed him and approached him on his way home one evening as has been said. Receiving from him the replies he had long sought, he engaged in long discussions with Mevlana, in whom he was convinced he had found the companion of his soul. For a long time after this first meeting, Mevlana and Sems became inseparable. Mevlana's son, Sultan Veled describes the first meeting of the two sages, and thejr subsequent friendship in his work the ibtidaname as follows: "Semseddin appeared, suddenly, and found Mevlana. He spoke to Mevlana of the philosophical heights of spiritual love. He drew back the curtain of esoteric devotion, bringing light to Mevlana's world. The shadow of Mevlana was dissolved in his light. At first all his followers were guided by Mevlana, and drew from him spiritual strength. Now, Mevlana was guided by Sems. Together they attained a vision of the graces of God." Through Sems spiritual guidance, Mevlana attained the ultimate level of mystical understanding of God. Sems, for him, was the manifestation of all that was of everlasting beauty. He was inebriated with the divine beauty in him, and Sems delighted in the extremity of his passion. He enlightened Mevlana by their discussions, and at the same time found in him the answers to questions of his own. In one of his lyric poems, Mevlana exclaims: "it was the time before dawn. In the sky rose a shining moon, it rose and stared at me. it hunted me as the hawk hunts its prey , rising with it into the sky . Rising with me into the heavenly spheres, it drew my soul from its human frame. In that sphere of spiritus, I was blind to all but the moon which bore me upwards.."
While Sems and Mevlana were engaged in such ecstatic exchanges, Konya was disturbed by the change in its great spiritual and philosophical leader. His sudden disappearance from the mosque and madrasa was incomprehensible to the majority of his followers. At first they were tolerant towards his new-found mystical relationship with Sems, but when their intimate discussions went on for weeks and months, some opposition was felt, some saying 'Who is this dervish named Sems that he takes him away from us to another sphere? He has distanced him from his followers, his students, from his books. Is he a magician or a sorcerer , what is he?' In time, Jealousy of Sems grew to a pitch among Mevlana's followers, some of whom began to threaten him, and finally one day in February, 1246, Sems disappeared quite without trace, as he had come.
Mevlana was greatly distresses by Sems' sudden disappearance. He was left in a spiritual emptiness which he expressed in lyric poems full of longing for Sems. His only solace was in Sultan Veled, his son and the only one of his followers to sympathise with him. For several years nothing was heard of Sems until one of the dervishes, returning from a visit to Damascus, brought news of him, saying that he had seen him in Damascus. Mevlana immediately gave a letter to the dervish, and sent him back to Damascus to bring Sems to Konya. Sems, however , refused to come. Two more letters of invitation were sent without success. Finally Sultan Veled himself took the fourth letter to Sems (who was still in Damascus) to whom he repeated Mevlana's entreaties. Sems was finally persuaded to return with him.
On his return, Mevlana again closed the doors of the madrasa and engaged in long discussions with his spiritual mentor. He gave Kimya Hatun, his adopted daughter to Sems in marriage and ensconced him in a corner of the madrasa. Meanwhile those opposed to Sems renewed their schemes to remove him, this time drawing Mevlana's younger son, Alaeddin Celebi into their plots. They blamed Sems for the death, at an early age of his wife, Kimya Hatun. ''The poor girl died of grief'' they said... ''Who could bear this Sems?'' Plots against Sems began to take shape, and on the night of the 5 December, 1247, he was waylaid with great cunning, it is thought, and was never seen again. Hiding the truth from Mevlana, his followers tried to comfort him saying: ''Sems has gone again, but he will be back one day''.