The founder of the Kiev Caves Lavra, St. Anthony, was born at the beginning of the XI century in the city of Lyubech (near Chernigov) and was baptized as Antipas. From a young age, he felt attracted to a higher spiritual life and, inspired from above, decided to go to Mount Athos. In one of the Athos monasteries, he took vows and began a secluded life in a cave near this monastery, which is still shown. When he gained spiritual experience in his exploits, the abbot gave him obedience so that he would go to Russia and establish monasticism in this newly enlightened Christian country. Anthony obeyed. 
When St. Anthony came to Kiev, there were already several monasteries founded by the Greeks at the request of the princes. But Saint Anthony chose none of them, and settled in a two-walled cave excavated by Presbyter Hilarion. It was in 1051. Here Saint Anthony continued the feats of strict monastic life, for which he was famous on Mount Athos: his food was black bread every other day and water in extremely moderate quantities. Soon his fame spread not only in Kiev, but also in other Russian cities. Many came to him for spiritual advice and blessing. Some began to ask him for a residence permit. The first was a certain Nikon, a priest, and the second was St. Theodosius.
St. Theodosius spent his youth in Kursk, where his parents lived. From an early age, he discovered a pious spirit: he visited the temple every day, diligently read the word of God, and was distinguished by modesty, humility, and other good qualities. After learning that the liturgy was sometimes not served in the church due to a lack of prosphora, he decided to take up the matter himself: he bought wheat, ground it with his own hands, and brought baked prosphora to the church.
For these exploits, he suffered a lot of trouble from his mother, who loved him dearly, but did not sympathize with his aspirations. Having once heard the Lord's words in church: "Whoever loves his father or mother more than me is not worthy of Me" (Matthew 10:37), he decided to leave both his mother (his father was already dead) and his hometown and came to Kiev to St. Anthony. "Do you see, my child," Anthony asked him, "that my cave is modest and cramped?" "God himself has brought me to you," replied Theodosius, "and I will do what you command me."
When the number of the companions of the Rev. Anthony grew to 12, he retired to a nearby mountain, dug himself a cave here and began to asceticism in seclusion. Theodosius remained in his former place; soon he was elected abbot by the brethren and began to try to establish a proper dormitory according to the charter of the Tsaregrad Studian monastery. The main features of the dormitory he established were as follows: all the property of the brethren should be shared, time was spent in incessant labor; labor was divided according to the strength of each abbot; each work began with prayer and the blessing of the elder; thoughts were revealed to the abbot, who was the true guide of all to salvation. The Monk Theodosius often went around the cells and observed if anyone had anything superfluous and what the brethren were doing. Often at night he would come to the door of the cells and, if he heard two or three monks conversing together, he would bang on the door with a baton, and in the morning he would denounce the perpetrators. The monk himself was an example to the brethren in everything: he carried water, chopped wood, worked in a bakery, wore the simplest clothes, and came to church and monastery work first. In addition to ascetic feats, the Rev. Theodosius was distinguished by his great mercy to the poor and his love of spiritual enlightenment, and he tried to win over his brethren to them. He built a special house in the monastery for the poor, the blind, the lame, and the paralyzed, and devoted a tenth of the monastic income to their maintenance.
In addition, every Saturday he sent a cartload of bread to the prisoners in the dungeons. From the writings of St. Theodosius, we know: two homilies to the people, ten homilies to the monks, two epistles to Grand Duke Izyaslav, and two prayers.
Founded by St. Anthony and organized by St. Theodosius, the Kiev Caves Monastery became a model for other monasteries and was of great importance for the development of the Russian Church. Famous archpastors, zealous preachers of the faith and wonderful writers came out of its walls. Saints Leontius and Isaiah (bishops of Rostov), Nifont (Bishop of Novgorod), St. Kuksha (enlightener of the Vyatichs), and the writers St. John the Baptist are particularly famous among the saints who took tonsures at the Kiev Caves Monastery. Nestor the Chronicler and Simon.