Is it that they can't be phrased or that you can't phrase them? I often have thoughts that I can't express through drawing, but that doesn't mean it is an impossibility. I think that we often ignore that the act of putting ideas or thoughts to words is a skill that can be made easier through training.
Ok, but now supposed that you never tasted strawberrys. How do I describe in language the flavor of strawberry to someone who never tasted them? I can make an approximation based on flavors you know, but once you taste strawberrys you realize that, although what I said is true, it does not convey the sensation of eating strawberrys at all.
Even more: the less types of fruit you have tasted, the harder it is to convey an approximation of the flavor of strawberrys through language. So a lot hinges on culture and shared experiences.
Languages come from different cultures and sets of shared experiences, so it is natural that they develop more conceptual density in some things than others, and it is also natural that the grammar more naturally fits a certain way of thinking and seeing the world. You can discuss German philosophy in English, but it is a bit clunky. If you ever had the experience of learning a foreign language, you probably felt that you achieved proficiency when you were finally able to "bend" your thought process like the locals do.
http://www.maps.org/images/pdf/books/HuxleyA1954TheDoorsOfPe...
I can't turn senses into words. I can't stare at a scene and capture the equivalent of a photograph by talking. But any thoughts I have about the strawberries or the scene, I can put into words.