Leonardo da Vinci was born into a time and place extraordinarily supportive of his wondrous talent. The mid-1400s saw the flowering of the Renaissance in Italy, supported by the art-loving Medici family currently in power: People were coming to appreciate Greek and Roman art in new ways; and great advances in scientific instruments and mathematics led to an interest in perspective in painting. Painters like Leonardo were interested in achieving a beauty on par with the ancients, and at the same time they were trying to surpass them in accuracy and realism.
During Leonardo's time artists still worked under the guild system: a young boy would serve as an apprentice to an accomplished artist, and would eventually take on his own apprentices. When Leonardo became an apprentice in Verrocchio's workshop, his experience was similar to that of an experience in any other trade, from tailoring to carpentry. Paintings were not the passionate expression of a single artist's mind. They were collaborations, painted according to the specifications of a patron. Paintings were the product of a studio, not of an artist. However, Leonardo helped to change the role of the artist: he himself became famous as an individual painter, a celebrity in his own right. He made being an artist a profession, and not just a trade.
Art was not the only aspect of culture that saw increased activity during the Italian Renaissance. Politics also buzzed with energy, both negative and positive. The Italian states were all independent, and were constantly involved in shifting alliances, allowing for little stability but much intrigue. Many of the Roman Catholic Church's most vile popes date from this period; Florence, where Leonardo lived, was the capital of the state of Tuscany, which was sometimes allied with the pope and sometimes not. Milan, another city where Leonardo spent a great deal of time, was the capital of Lombardy, which was repeatedly invaded by the French.
As the various Italian states vied for power, so, too, did the Church. As far as art is concerned, the Church funded a great deal of work, and there was a clear distinction between art that was "pious" and art that was "profane"; thus it dictated much of what art portrayed and didn't portray. Leonardo often received commissions to do work for monks, and if his work did not meet the exact pedagogical specifications of the monks, he was asked to change it. The Inquisition, which was a program to seek out and execute non-believers, was initiated during Leonardo's lifetime.