Mystery is at the core of corporate law. The first question in corporate law is also the last: what is a company? It is a question that the legal philosopher HLA Hart (1983, 23) would prefer we did not ask, but given the centrality of companies to modern life, we cannot help ourselves as long as the fundamental issue of their essential nature remains contested. This chapter uses a historical lens in an attempt to identify what exactly a company is. It concludes that the modern company is a legal person that is an entity created by statute comprising a fund. The chapter shows that the modern form of the company as separate from shareholders is a consequence of default limited liability being granted in the mid-nineteenth century, although its consequences and benefits were not fully realized until later in the century. This analysis focuses on the English story but is of wider interest because the development of the modern business corporation followed a broadly parallel path in most jurisdictions.