What must be taken into account in any consideration of the Baroque is the equilibrium of the secular and the religious. The naturalism of seventeenth-century art is inextricably bound up with a metaphysical view of the world. It is for this reason that the familiar objects of visible reality may be looked on as emblems of a higher, invisible reality. But that transcendent world can in turn only be apprehended through the faithful rendering of things seen. In this sense, naturalism may even be said to play an ancillary role, its function being to reveal the spiritual through the medium of the senses. This attitude, it is hardly necessary to say, was not peculiar to artists.

Many of the leading scientists of the seventeenth century entertained mystical notions about the physical universe which they were seeking to describe in mathematical terms. The Baroque concept of art as persuasion was applied to architecture as well as to the figurative arts. Baroque architecture was brought to its highest emotional pitch in Spain and southern Germany in the eighteenth century. There is something positively hallucinatory in the excesses of the Transparent e in Toledo Cathedral. A similar sensationalism fills the Bavarian churches of the brothers Asam.

In the interior of the abbey church at Weltenburg spatial illusionism and dramatic lighting are all-important. The inner dome that crowns the oval nave is cut off so that one looks through it to a higher painted ceiling, which receives its light from concealed windows. But the most extravagant illusion is reserved for the high altar within its darkened chancel, where St George on horseback, all in shining silver, rides through a light-filled archway to slay the dragon and rescue the princess. It is a gorgeous spectacle, and one that is calculated to raise the religious passions of the worshipper to new heights of ardour and excitement. The most distinctive feature of Baroque architecture is its mastery of space. And it is just to this controlled movement of space, both interior and exterior, that we must look to find the closest affinity with the representational arts.

The forecourt principle employed by many architects bears an evident relation to the development of a field of force in front of the work of painting or sculpture. On the facade of the Barberini Palace in Rome, Carlo Mader no, and after him Bernini, did away with the traditional fortress-like wall of the urban palazzo and threw open the whole central mass of the building in three tiers of loggias, as if the enclosed courtyard of a 'normal' palace had been unexpectedly revealed to public view [152, I 52 A]. The resulting flow of space from the forecourt into the very heart of the palace corresponds to the illusion of coextensive space in the figurative arts. The methods adopted by Italian architects of the seventeenth century to affect this kind of spatial interpenetration are wonderfully varied and imaginative. Pietro da Cortona, remodeling the front of S. Maria della Pace, dramatizes the entrance by setting before it a semicircular portico, the expansive rotundity of which is countered by the concave arc of the wings that en frame the upper storey of the facade, while the columns of the porch seem to group themselves in such a way as to give free access to the interior. A similar interplay of convexity and concavity of spatial advance and retreat may be observed in Bernini's church of S. Andrea al Quirinal e.

The visitor approaching the building at once feels himself engaged by the bold thrust of the columned porch, the semicircular steps and the curving walls at the sides.