The Annunciation, with Saint Emidius, Carlo Crivelli.
In the National Gallery, London. Use the fullscreen and zoom tools to the right of the image.
There is also a large image on Wikimedia.
The early 15th century saw both linear geometrical perspective construction and the medium of oil painting come into common use in European painting (see my post on Jan van Eyck).
Here, Crivelli has a field day with both, and despite his apparent struggles with the proportions of hands and the shape of eyes (see my post on Rogier van der Weyden), creates a striking image of the Annunciation.
I love the cornucopia of little details, the fanatical attention to texture, the luxurious use of color and the nifty way the composition has the ray of divine inspiration reach the figure of Mary through a portal in the building wall. (You buy it, even though the angle is completely wrong; but hey — master of time and space, right?)
And then, of course, there’s the apple and the pickle…
Another example of my assertion that these painters were the special effects wizards of their day (see my post on Antonello da Messina), creating stunning visuals that wowed the faithful in altarpieces that in themselves were reason enough to attend church services.