In "The Worst Crime in the World" by G. K. Chesterton, the author was saying in its beginning:
FATHER BROWN was wandering through a picture gallery with an expression that suggested that he had not come there to look at the pictures. Indeed, he did not want to look at the pictures, though he liked pictures well enough. Not that there was anything immoral or improper about those highly modern pictorial designs. He would indeed be of an inflammable temperament who was stirred to any of the more pagan passions by the display of interrupted spirals, inverted cones and broken cylinders with which the art of the future inspired or menaced mankind.
What's meant by these obscure geometrical shapes, and what's the whole meaning of that sentence?