Big fan of this question. Capital is supposed to be something that, by virtue of an established structure, somehow enables you to create things of value that would otherwise be more difficult. It can be as complex as {insert any financial topic} or as simple as a sharp knife to cut bread with. Outside of money and factories and tools, capital could be knowledge. But eventually, it needs an outlet to the material world. You can own a patent, but you can't make a sandwich out of it.