Why did Nicolas Poussin stop pursuing a career as a public painter in Rome?

Nicolas Poussin’s decision to stop pursuing a career as a public painter in Rome was prompted by the reception of his 1628 commission for The Martyrdom of St. Erasmus, an altarpiece intended for St. Peter’s. The work failed to meet with critical acclaim, which effectively ended his pursuit of public commissions in the city.1

Following this experience, Poussin chose to shift his focus toward creating easel pictures characterized by greater subtlety and refinement. He subsequently devoted much of his artistic output during the late 1620s to romantic mythologies, drawing inspiration from Titian and other Venetian masters. This transition marked a departure from the public sphere, allowing him to develop the rational and disciplined style for which he later became renowned as the founder of the French Classical tradition.12