In the late 16th century, a new way of dealing with artistic subjects was born, largely through the influence of one man: Michelangelo Carisi da Caravaggio.
Before him, art still reflected the idealistic vision of the Renaissance, based on the classical Greek and Roman models.
Caravaggio discovered a new way of painting and his influence has filtered right down to the present day: you can see examples of his Baroque style among the fine art for sale in any art gallery.
What were these new approaches? Firstly, the subject matter was dramatic and realistic, designed to draw you in and perhaps even shock you, rather than letting you simply admire an image of ideal beauty from afar.
To achieve this more natural style, light and shade were used to highlight or darken certain features using a technique called chiaroscuro.
The use of such dramatic shadowing was called Tenebrism, and it worked rather like a theatrical spotlight, allowing the artist to be more in control of how the viewer regarded his work.
In his choice of subject matter, this artist also brazenly broke the rules.
Instead of producing the kind of noble, uplifting pictures that the Catholic Church approved of, Caravaggio depicted exactly what he saw around him.
He often put paint straight onto canvas, dispensing with preliminary sketches, and his models were drawn from the streets of Italian cities and were often disreputable characters - rather like the artist himself, who frequently got into trouble for drunken brawling and homosexuality.
Even when painting a religious subject, Caravaggio would give it his own inimitable twist.
In the 'Calling of St Matthew,' for example, the painting is dramatically slashed in half by a diagonal shaft of light from the top right, with much of the lower half in shadow.
This highlights the faces of the men who are looking at Christ, and contrasts with the figure of Matthew, the tax-collector, whose head is down while he is counting his money.
Three of the figures have their forefingers highlighted, all pointing at Matthew, making a very theatrical composition that cannot fail to spell out its message to the viewer.
Caravaggio's revolutionary techniques kick-started the Baroque period, and led to the triumph of realism over idealism in art.
Soon he began to have followers, called 'Caravaggisti,' who carried on the new style of painting which led to fine old masters, such as Rubens and Rembrandt.
Centuries later, his influence can still be seen in the work of French painters in the nineteenth century: the Realist movement that drew inspiration from painting the ordinary daily life of the working classes, and the Impressionists' fascination with light.
Yet not long after his death this revolutionary painter was almost completely forgotten, perhaps because of his notorious personal reputation, and it was only in the twentieth century that his work and influence were rediscovered.
Now you can find his style of fine art for sale in almost any art gallery, because he could be considered the father of modern art.