# Combining Graphics & ContourPlot using Show

I was recently experimenting in Mathematica and was combining graphics and a contour plot and discovered the order of elements in show matters. Why would the order matter here?

Remove[g,c];
g = Graphics [Arrow[{{0,0},{1,1}}],PlotRange->{{-5,5},{-5,5}}];
c = ContourPlot[x^2+y^2,{x,-5,5},{y,-5,5}];
{Show[g,c],Show[c,g]}


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Options are taken form first Show element, that is why there is/isn't Frame. Arrow is behind ContourPlot in first Show. –  Kuba Jun 4 at 21:12
–  Kuba Jun 4 at 21:22
You can see that the area is under the contour shading by setting ContourShading->None in the ContourPlot. –  Mark McClure Jun 4 at 21:27
One way to think about it: When you paint a house, which color do you see, the primer (first coat, white) or the final coat? And if the paint is not completely opaque, you might see color from the undercoat. –  Michael E2 Jun 5 at 0:03
@Mark, it might be more convincing for OP if he uses something like ContourShading -> Opacity[1/2], I'd bet. –  Ｊ. Ｍ. Jun 5 at 1:21