A share price tells you what the market thinks a company is worth today. It says nothing about how the company got there.
Two businesses can report the same net income and be very different. One collects cash from customers within weeks. The other books revenue on invoices that may take months to be paid, or never are. One capitalizes costs that the other runs straight through the income statement. Earnings per share look alike, the P/E looks alike, the quality does not.
The difference sits in the cash flow statement, in the notes, in the accounting policies section that most investors skip. That is where a P/E stops being a ratio and starts telling you what the earnings are made of.
You can invest without reading any of it. The price will be there every morning at 9:00. What you will not have is a view on whether the profit behind it is cash, estimate or timing.
Double Entry Life starts from that gap: accounting as a way to see what a number is made of.