A theme is a<span> set of unified design elements and color schemes.</span>
The answer is it then remain preserved over the centuries. Since a layer of the volcanic ash preserve the art and architecture to the residents, the city of Pompeii then provide a snapshot of the Roman art.Hope this would be of help.
Chiaroscuro is Italian for<em> light and shadow</em>
Painters use this technique when they need to <u>create the illusion of light</u> on objects and people
I've attached a pic for example :D
I believe we didn’t accept abstract as art for so long because it was different. When things are different we often (as humans) avoid it or think less of it. In this case it’s art. People often think there is a handbook to creating art. But there isn’t which is why abstract art was not accepted. You had to develop a story for it instead of it developing a story for you.
Hope this helped!!