how did sandro botticelli look back to the classical past in his painting
Botticelli’s star was in the ascendant. Such was his reputation that, in 1481, he was summoned by the Pope to Rome to help decorate the walls of the recently completed Sistine Chapel in the Vatican. He painted frescoes depicting scenes from the Life of Moses and the Temptations of Christ and was also responsible for a number of papal portraits. The nature of this task demonstrates how highly regarded he was around this time, and it was the only occasion he is known to have worked outside Florence.
[1 ] At the height of his fame, the Florentine painter and draughtsman Sandro Botticelli was one of the most esteemed artists in Italy. His graceful pictures of the Madonna and Child, his altarpieces and his life-size mythological paintings, such as ‘Venus and Mars’, were immensely popular in his lifetime.
Another older theory, assuming an early date, suggests the older Lorenzo commissioned the portrait to celebrate the birth of his nephew Giulio di Giuliano de’ Medici (who later became Pope), but changed his mind after the assassination of Giulo’s father, his brother Giuliano in 1478, having it instead completed as a wedding gift for Lorenzo di Pierfrancesco.  
The interactions between the figures are enigmatic. Zephyrus and Chloris are looking at each other. Flora and Venus look out at the viewer, the Cupid is blindfolded, and Mercury has turned his back on the others, and looks up at the clouds. The central Grace looks towards him, while the other two seem to look at each other. Flora’s smile was very unusual in painting at this date. 
Of obvious importance in this painting is the nudity of Venus. The depiction of nude women was not something that was normally done in the Middle Ages, with a few exceptions in specific circumstances. For the modeling of this figure, Botticelli turned to an Aphrodite statue, such as the Aphrodite of Cnidos, in which the goddess attempts to cover herself in a gesture of modestly.
Sandro Botticelli, Birth of Venus, c. 1484-86, tempera on canvas
The bronze was initially installed in Palazzo Vecchio in 1476.
As in many of Leonardo’s paintings, the composition comprises a pyramidic spiral and the sitter is caught in the motion of turning to her left, reflecting Leonardo’s lifelong preoccupation with the dynamics of movement. The three-quarter profile portrait was one of his many innovations. Il Moro’s court poet, Bernardo Bellincioni, was the first to propose that Cecilia is poised as if listening to an unseen speaker.
During BotticelliвЂ™s youth, Florence was the center of innovation in Italian art. The Florentine sculptor Donatello used his extensive knowledge of classical works to push his art to new heights. The Dominican Basilica of Santa Maria Novella housed the вЂњHoly TrinityвЂќ fresco by Masaccio. Completed in 1427, it is believed to be the first work to fully apply the laws of linear perspective. (See also: Finding Donatello’s ‘Lost’ Masterpiece.)
Cosimo deвЂ™Medici came to power in 1434 and immediately set about an extensive building program, including finishing Filippo BrunelleschiвЂ™s gravity-defying cupola on FlorenceвЂ™s duomo of Santa Maria del Fiore. All this new architecture created a demand for works of art to fill them, which artists were only too happy to supply. (See also: Brunnelleschi’s Dome.)