The sky and ocean are not always blue.<p>For most cultures on Earth, the last color they named was blue --- this is thought to be due to its rarity in nature.<p>Up through the Renaissance, the pigment for blue paint was made from Lapis Lazuli which made blue a very expensive paint and rare in most art. This is another sign of the rarity of blue in nature as pigments for other colors were much easier to come by.<p>I haven&#x27;t listened to this episode of Radiolab in a while, but I think it provides more info&#x2F;source on both of these points: <a href="http:&#x2F;&#x2F;www.radiolab.org&#x2F;story&#x2F;211119-colors&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.radiolab.org&#x2F;story&#x2F;211119-colors&#x2F;</a><p>There is also an interesting anecdote where one of the interviewees tells the story about teaching his daughter colors. He and his wife made the decision not to tell her what color the sky was; he would go on walks with his daughter and ask her to identify the colors of various plants and objects, when asked about the sky for a while she didn&#x27;t have an answer and when she finally did she said its as &quot;white&quot; not &quot;blue&quot; --- which does seem like a better way to describe the sky since even on a clear day the brightest parts can look almost white; but someone told me once it was blue.