I remember reading in another question about Time Travel here on the forum, with the subject of your being stuck in medieval time. That if you where lucky, you could have a good life serving your local noble/lord, as an accountant and maybe as a writer, and with your modern day high school math would be able to elevate his status in the king´s courts.

How exactly would such a thing as you knowing modern day math and being able to read and write, do anything for the nobleman's status in the king´s court? Surely even if the nobleman wasn´t the brightest, he would still have people hired to do something so basic as laying down a budget? Or have I misunderstood something about medieval society worked?

If so, I would be grateful, if someone could explain or point out a post where this explained? Because as said I have a hard time seeing how modern day high school math and maybe being bright enough to learn how to read and write in medieval language, would in anyway shape or form help the nobleman in any way shape or form that would help his rise in status in the kings court.

  • $\begingroup$ "Something so basic as laying down a budget: do you actually have an example of anybody preparing a resonably sound budget for a moderately large project at any time during the western European Middle Ages, say between the 6th and the 15th century? (No cheating; the (Eastern) Roman Empire, the Arab empires and the Chinese don't count. Western European medieval please.) $\endgroup$
    – AlexP
    Mar 6, 2021 at 23:48
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    $\begingroup$ @AlexP, you mean like the one documented in the Burghal Hidage, dating from around 914, which documented the annual budgetary requirements (in terms of both money and manpower) required to maintain the military-economic system of burhs in the Kingdom of Wessex? $\endgroup$ Mar 7, 2021 at 5:06
  • $\begingroup$ @KeithMorrison: Yes, that's the kind of static tracker I had in mind when I said that they had no concept of how to prepare a budget. There are many such documents preserved from the Middle Ages; what they have in common is that they are in the nature of static shopping lists / checklists. The military commander or tax collector went down the list item by item and ticked off each item. From Hastings 800 men, check. From Winchester 2400 men, check. A budget is on the contrary a forward-looking document, on the basis of which such checklists / trackers are then made at each step in the project. $\endgroup$
    – AlexP
    Mar 7, 2021 at 8:23
  • $\begingroup$ @AlexP You mean like an army commander calculating how many men, how much equipment, and how much time it would take, to breach an enemy fortification? Budgets do not always start out as monetary planning, although they eventually turn in to a monetary planning exercise. $\endgroup$ Mar 7, 2021 at 15:49
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    $\begingroup$ The Time Traveler's high-school education in basic physical sciences, earth and environmental sciences, health and nutrition, and their hazy knowledge of future events will get them burned as a witch long before they can prove their mettle doing long division. Most medieval cultures were not meritocracies. $\endgroup$
    – user535733
    Mar 7, 2021 at 19:01

4 Answers 4


From Wikipedia, on accounting:

Double-entry bookkeeping was pioneered in the Jewish community of the early-medieval Middle East and was further refined in medieval Europe. With the development of joint-stock companies, accounting split into financial accounting and management accounting.

The first published work on a double-entry bookkeeping system was the Summa de arithmetica, published in Italy in 1494 by Luca Pacioli (the "Father of Accounting").

And about Descartes:

One of Descartes's most enduring legacies was his development of Cartesian or analytic geometry, which uses algebra to describe geometry. Descartes "invented the convention of representing unknowns in equations by x, y, and z, and knowns by a, b, and c". He also "pioneered the standard notation" that uses superscripts to show the powers or exponents; for example, the 2 used in x2 to indicate x squared.

We often take these things for granted.

I have been in the position of someone transported to a place where people don't know basic math often enough that I can sympathize with any time travelers going to the middle ages. In my case, it was more like being an IT pro with more than one boss who got their position through the Dilbert principle. Seriously. I once made a piece of software that would keep some people from using some company accounts if they went overbudget for the month. I had to explain this to my boss multiple times, and he still wouldn't have it.

"How come we are over budget if there is still money in the account?"
"Well, there are some expenses that the company has to pay for in a few days. You use that money now, you won't be able to pay everyone's salaries and the electricity bill"
"I still don't get it, this system sucks! Turn it off!"

There's this book I really love, called "The Richest Man of Babylon". It tells the story of a filthy rich merchant in ancient Babylon who is tasked by the king with teaching basic math to his subjects so that the realm can generate more wealth. In one of the lessons, rich guy tells everyone that they must have a budget. A young guy gets mad at the notion that he must be a slave to a table and ragequits the class. He ends up poor while most others end up rich.

You've seen it too. Every one has at least one friend or relative who sucks at budgets, and is always either wasting money on superfluous things or getting into debt without actually having to. In order to stop sucking at budgets, the very least you have to do is a table with incomes and expenses, which is a rudimentary way of bookkeeping. People who suck at math or can't read and write will have a very hard time at this. In the middle ages most people would fit into one group or the other, sometimes both.

So if you are able to make good choices with money, you could keep your overlord from going bankrupt. If you're really smart and clever, or if you graduated in a STEM course you can probably come up with a system of your own that will improve the local economy a little bit. But if you are an actual accountant? You might be interested in reading about the Medici family in Italy. They opened a bank that lasted from 1397 to 1494 and made them the wealthiest family in the western world until incompetence caused the bank to be liquidated. You could probably replicate the feat in earlier dates, and even make it more durable since you'd have further financial and historical knowledge.

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    $\begingroup$ Illiterate people can keep track of income and expenses mentally. Indeed, owing to practice, much more than literate people can. $\endgroup$
    – Mary
    Mar 6, 2021 at 21:33
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    $\begingroup$ @Mary: That's cash-based accounting and it is older than the hills. It is also of very limited usefulness as a tool for preparing budgets for moderately large and long projects and for following the execution of those budgets. Double-entry book-keeping was invented for a very good reason, not because accountants needed more work. $\endgroup$
    – AlexP
    Mar 7, 2021 at 0:12

Money supply. The medieval noblemen probably have little idea of the concept. If your accountant can educate his nobleman in the art of lending money he doesn't have as paper promises to pay in exchange for future goods, waiting for the ensuing inflation to increase the price of gold and grain before selling his reserves, and then calling in his paper debts ... well, the peasants may not live to see the 20th century, and the accountant's descendants can take their place.

Lending options. The noblemen probably only have a few ways they lend out money, and those are likely subject to the quaint tradition of usury laws. The accountant can instruct the noblemen in the art of extracting a fee - not usury, mind you - to issue a workman's payday wages early, just this once - well, the sky is the limit. He could find himself moving to a royal court if he's not careful.

Credit rating. Peasants have a credit rating - stinking, ignorant, base-born nobodies ... wait, no, there's a better way to do it! When the nobleman sends his henchmen around to "tax" the peasants for all their accessible cash, they can explain that prompt, courteous compliance (plus sufficient cash) will get the peasants a Good Mark that will follow them and their descendants until the mountains crumble into the sea. The same for other financial arrangements of benefit to their Lord. If their dear mother takes ill after the tax collectors have taken all the money, how will they buy medicine if they don't have a good Credit Rating? Before long the peasants will be diligently turning up for occasional high-priced payday loans to try to show their noble lord that they are Good People and should be rated as such. Taking time to sneer at their weaker-fortuned fellows on the way out.


If this is a time traveler to earth's medieval past there is a problem. Modern finance is not relevant to banking at that time.

The problem was that the Catholic Church forbid charging interest. This killed banking as we know it today.

What was done which was allowed and was done in part to get around this were Bills of Exchange. With these, one could pay in one country in one currency for a payout in another country and currency at another time. You could borrow by getting the payout now and pay back later. It was also a way to transfer money between cities.

Traveling merchants and merchants buying inventory from other cities used these. They could have a financial family pay for the purchase of inventory in another city. The goods were transferred to the retailer who would pay on the Bill of Exchange from the sale of the items.

Although you could not charge "interest" you could charge for foreign currency exchange. Banks do this by baking there fee into the ratio of the currencies that they exchange. You will notice the ratio of currencies a bank lists is different depending on which one you are exchanging for the other.

So this became the only banking going on in Catholic Europe. So a modern accountant would face this problem. Their skills would not match and they would have to learn how finance works here.

Maybe the account could try setting up commodity futures trading. This is a modern notion which could be seen as a way to stabilize prices so might not get disagreement with the Church.

  • $\begingroup$ I thought the banks got around this by introducing a small fine for late payments. As such if you payed on time, well the banks wasn´t really interested in lending you more money. So it became almost expected among their customers to payback their loans a little late, pay the fine, in order to make sure that the bank would still lend you money in the future. So maybe our time traveler could use that system to work with? $\endgroup$
    – Gridlock
    Jun 30, 2021 at 6:36
  • $\begingroup$ Yes, and I had some regret not covering that. So you could not charge interest on a loan. But you could make a loan for 6 months, and after 6 months charge them for regular "late" payments. A time traveler could indeed use that too. My point was they would have to learn new systems so wouldn't have complete advantage from their later "advanced" knowledge. $\endgroup$ Jun 30, 2021 at 12:10

It would have absolutely no effect.

The problem with time travel that is so often missed is 'memory'.

A time traveler could not 'remember' any data that was obtained in the future, because of the light cone. Causation would have to come after the effect.

So even if an accountant today could travel back in time, his memory would not follow him. He would not be able to remember any modern-day information, as the cause of it would not yet have occurred. The only thing he could 'know' or 'remember' was the information available in the time period he was in.

In point of fact, it is doubtful if he could even know or remember that he was a time traveler.

  • $\begingroup$ If you can send back a body/person, memory is just en extension of that. A body represents a huge amount of information, memory is a subset of that. E.g. I don't see how sending a tablet computer back in time would erase the data. but sill allow operational hardware. $\endgroup$ Mar 8, 2021 at 20:01
  • $\begingroup$ @Gault Drakkor Which pretty much explains why nothing can go back in time. But the question specifically is about information and thus memory. $\endgroup$ Mar 9, 2021 at 2:33

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