# I didn't know that!

Arthur Mattuck(MIT Math Prof.) said:
....That's the usual way to do it. If you have the step size, since this is a constant, if I have the step size, I have the error, approximately. Have the step size, have the error. That tells you how the error varies with step size for Euler's method. Please understand, that's what people say, and please understand the grammatical construction. Since everyone in the math department has a cold these days except me for the moment, everyone goes around chanting this mantra.

This is totally irrelevant. This whole mantra, feed a cold, starve a fever. And if you asked them what it means, they say eat a lot if you have a cold. And if you have a fever, don't eat very much, which is not what it means at all. Grammatically, it's exactly the same construction as this. What this means is if you have the step size, you will have the error. That's what feed a cold, starve a fever means. And, remember this for the rest of your life. If you feed a cold, if you eat too much when you have a cold, you will get a fever and end up still having to starve yourself because, of course, nobody, when you have a fever, nobody feels like eating, so they don't eat anything.

All right, you got that? Good. I want all of you to go home and tell that to your mothers. You know, that's the way we always used to speak. Grimmer ones: spare the rod, spoil the child does not mean that you should not hit your kid. It means that if you fail to hit your kid, he or she will be spoiled, whatever that means. So, you don't want to do that. I guess the mantra today would be, I don't know. Okay, so the first line of defense is simply to keep having the step size in Euler....

I always thought that aphorism, "Feed a cold, starve a fever", was two separate phrases. That's interesting..

Ben Niehoff
Gold Member
Why does someone going on a grammatical tirade continue to write "have" when he means "halve"?

I don't think he wrote that. The was the transcript of one of his lectures.

I've never heard of anyone getting a fever as a consequence of eating a lot during a cold. Is there any authentic medical basis for his interpretation of that saying?

As far as most old wives' tales go, I don't think most of them have evidence, do they? Well, regardless of whether it's true or not, I was just pointing out that the interpretation was different

BobG
Homework Helper
As far as most old wives' tales go, I don't think most of them have evidence, do they? Well, regardless of whether it's true or not, I was just pointing out that the interpretation was different

That's because, while he may be good at math, he's lousy at old wives' phrases. He needed a binary condition and chose a poor one.

He might have fared better choosing the "Spare rod, spoil the child". You could come up with a decent analogy there. Beat the child, but stop once signs of PTSD start to appear. Start again once the signs of PTSD have started to subside and the child starts to turn into a tyrant.

Or, "have"[sic] the error by only slamming his fingers in a drawer instead of beating him with a shovel. Maybe the child won't veer all the way to suffering from PTSD. And slam his fingers in the drawer for everything he does wrong instead of waiting until the child has become a little tyrant.

Perhaps he felt he was treading on dangerous ground as soon as he started talking about physically abusing children. :rofl:

And math profs wandering around the halls chanting "I don't know" is why most students avoid the math department. (Well, that and the fact that math is hard.)

What a weird lecture that must have been!

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mgb_phys
Homework Helper
The language has changed to put the proverb the opposite way around.
Starve used to mean dying (of anything - not hunger), it still does in the north of England. My gran used to say "starved wi cold" to mean she was cold.

So feed a cold starve a fever - really means if you eat too much when you have a cold you will die of fever.

As far as most old wives' tales go, I don't think most of them have evidence, do they? Well, regardless of whether it's true or not, I was just pointing out that the interpretation was different
I've certainly never heard that interpretation.

However, one could make a good case for "An apple a day keeps the doctor away," having good basis in fact: back in the day sailors whose diet had no fruits or vegetables eventually developed scurvy.

So feed a cold starve a fever - really means if you eat too much when you have a cold you will die of fever.
That's more severe than the lecturer's interpretation, clearly, but still consistent with his view of how we should understand the grammatical construction.

I'm not adverse to re-interpreting the saying that way if someone could point to some reason it was ever supposed eating too much when you had a cold would cause you to get, or die of, a fever.

That's more severe than the lecturer's interpretation, clearly, but still consistent with his view of how we should understand the grammatical construction.

Is it? I'd say that was exactly what he was trying to convey.

Is it? I'd say that was exactly what he was trying to convey.

"if you eat too much when you have a cold, you will get a fever and end up still having to starve yourself because, of course, nobody, when you have a fever, nobody feels like eating, so they don't eat anything."

Clearly he's saying you will starve for the duration of the fever, but there is no guarantee of death as in the interpretation offered by mgb_phys:

"...if you eat too much when you have a cold you will die of fever."

Am I supposed to eat when I have a cold or no? Jebus i have a cold and I need to know. I for one do not want to die of a fever.

Am I supposed to eat when I have a cold or no? Jebus i have a cold and I need to know. I for one do not want to die of a fever.
From now on whenever someone asks me what to do about a cold I'm going to say: "If you have the step size, you have the error".

turbo
Gold Member
When I have a cold, I cut out all dairy, eat light, and drink clear liquids like teas and fruit juices. I can't take antihistamines, so anything that I can do to reduce mucus production is a plus. Green tea, hot cider with a cinnamon stick, etc are soothing and give you a little shot of antioxidants - might help, and can't hurt.

BTW, the way I heard that phrase when I was a kid is that you should starve a cold and feed a fever. Makes sense, because when you are running a fever, your body is metabolizing its resources at a higher rate than normal, so you need to keep refueled.

mgb_phys
Homework Helper
People used to think that eating took a lot of effort.
I'm guessing that the full, lethargic feeling after you eat - especially when your diet was more carbs than protein, seemed like a disability or closer death.
The saying is at least C16th and starved =to die is much older, but the same thing is in C19th century. Sherlock Holmes doesn't eat when he is thinking in a difficult case because he cannot afford the energy of digestion.

Moonbear
Staff Emeritus
Gold Member
That's more severe than the lecturer's interpretation, clearly, but still consistent with his view of how we should understand the grammatical construction.

I'm not adverse to re-interpreting the saying that way if someone could point to some reason it was ever supposed eating too much when you had a cold would cause you to get, or die of, a fever.

There's no basis to it whatsoever, especially since you can still run a fever with a cold. Though, if you have a fever, you probably don't feel much like eating. Whenever I've had a fever, I've always forced myself to eat no matter how I felt, all part of staying hydrated and keeping up my energy to fight off the bug. Much to the chagrin of many, I'm still around.

There's no basis to it whatsoever, especially since you can still run a fever with a cold. Though, if you have a fever, you probably don't feel much like eating. Whenever I've had a fever, I've always forced myself to eat no matter how I felt, all part of staying hydrated and keeping up my energy to fight off the bug. Much to the chagrin of many, I'm still around.

If it's completely untrue about the common cold, then it occurred to me the saying might have originated from some epidemic disease that no longer exists whose symptoms consisted of bronchial congestion with increased appetite followed by prolonged fever and decreased appetite leading to death from starvation. I just find it hard to believe a saying like that could have arisen from nowhere and caught on so well.

I just find it hard to believe a saying like that could have arisen from nowhere and caught on so well.

Why is it so hard to believe? People think they swallow 8 spiders during their lifetime while asleep because somebody made it up and wrote it down.

Why is it so hard to believe? People think they swallow 8 spiders during their lifetime while asleep because somebody made it up and wrote it down.
Urban legends and wise old sayings are in two separate categories. "Feed a cold, starve a fever" is in such company as "A stitch in time saves nine," "An apple a day keeps the doctor away", "Don't put all your eggs in one basket", and "Don't count your chickens before they're hatched", all of which make sense. "Spare the rod, spoil the child" means (despite BobG): "Discipline your kids or they'll become self indulgent." Why should cold/fever be an anomalous, completely irrational one?

Evo
Mentor
Ok, here it is.

http://soundmedicine.iu.edu/segment/246/Feed-a-Cold--Starve-a-Fever- [Broken]

The adage "feed a cold, starve a fever" dates back to the 1500s, but according to authors Stuart and Doris Flexner in their book Wise Words and Wives' Tales, there has been debate about the actual advice since there are references to both feeding and starving a fever.

The current proverb, with the inclusion of feeding a cold, was recorded for the first time in 1852. The origin and meaning continued to be debated, however. And up until recently, medical professionals put little stock in the phrase.

But about a year ago, scientists in The Netherlands showed in a small study that two chemicals that regulate the immune system reacted significantly to both eating and fasting (feeding and starving). Following a liquid meal given in the laboratory, blood tests showed the subjects had a four-fold increase in the chemical gamma interferon -- a marker that measures immune response to viral infections. So they fed a cold and it worked.

Later, test subjects were given only water and blood tests revealed afterwards that the chemical interleukin-4, a marker for immune response against bacterial infections, had also increased four-fold. So starve a fever.

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Ok, here it is.

http://soundmedicine.iu.edu/segment/246/Feed-a-Cold--Starve-a-Fever- [Broken]
This, though, means the saying always meant what it sounds like it meant, and that the math professor who claimed everyone had it all wrong actually had his head up his Euler.

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