I learned that in basic book-keeping on paper, the key really was just "classification"; that is, understanding what category an account was in (not immediately obvious for things like depreciation/amortization, etc). That determined the perspective from which things are seen, and so debit/credits became clear. However this method turned out to be really unwieldy to program on a computer (I even tried to build a double-entry book-keeping spreadsheet on Excel but failed). The author's method is far preferable and far more programmable -- I wish I had this insight in college.
At the basic levels, book-keeping is about a couple of things:
1) Recording transactions in a "journal"
2) Posting from said journal to "accounts" (Dt/Cr) = i.e. double entry accounting
3) Doing reconciliations (e.g. bank reconciliation) to make your accounts consistent with some third-party
4) Doing cash flow analysis
5) Preparing Income Statements and Balance Sheets, which is used to analyze a company's cumulative/current position.
Most accounting courses cover these steps (called "book-keeping") but real "accounting" is more than this: it's about getting insights from these numbers, by calculating useful ratios, KPIs etc.
The real insight from accounting is being able to deduce a company's strategy from their financial statements. Apparently this is one of the things Harvard Business School teaches in their MBA program that few schools do.
Also, if you read lots of SEC 10-k filings (like Warren Buffet does), the claim is that one should be able to put together a story of what a company is doing by looking at how it's managing its money, what it is investing in, and so on.
Basically, think of the left side of your equation (expenses + income) as "not yours".
This is something which trips a lot of folks up, but it has a very simple explanation: in double-entry accounting money always flows from one account to another, e.g. from income to a bank account, or from the bank account to an expense. The income account is always negative because money is almost always leaving it, and the expense account is always positive because money is almost always entering it (I wrote ‘almost always’ in both instances because one might need to repay erroneous income or one might get a refund from an expense).
Plus, switching signs doesn't make it any easier to understand as a whole. A simple example: You're Blockbuster and a customer gives you $5 to rent a video.
Cash +$5
Income -$5
If we switched the signs, now our Income would be easier to understand (changed to a positive number), but Cash would be negative (and more confusing - why would it be negative when we received cash?)
Financial Income is in a denomination that is not yours. When you receive more of the denomination you are receiving more of somebody else’s liability to you.
That’s more negative (more credit)
All I can think of is to ensure that
Over any given interval of time. But really, adding a single minus sign in the above equation would make the rest of the story so much more intuitive to beginners. I wonder if this is just an ossified bad choice, or if I am missing something.edit: https://beancount.github.io/docs/the_double_entry_counting_m... answers my question.