It's therefore useful for our brains to construct notions like "solidity" and "impenetrability," because such notions help us to navigate our bodies through the middle-sized world in which we have to navigate.
ですから、我々がいる中くらいのサイズの世界を生きてゆく上で 我々の脳が「固い」とか「貫けない」といった概念を生み出すのは 便利なことなのです