At least, in the history of mead making:
To Boil or not to Boil?
This may seem a trifle but I once saw this debate come to blows. More than once I've seen it come close. Mead people get really worked up over this.
Should one boil honey before fermenting it?
Honey is basically an emulsion of simple and complex sugars and waxy lipids. Boiling the honey causes the emulsion to separate. If you've ever tried to heat hollandaise above a critical temperature you've noticed a similar phenomenon as the sauce split back into butter and egg yolk. When honey is heated slowly the solids, the wax, grit and bee effluvium separate from the sugars and float to the top. Along the way it becomes a sticky, slimy, foul smelling mess that is easily skimmed off the top of the mix and discarded. This process is time consuming and labor intensive.
There are advantages and disadvantages to boiling. I'm going to go over both and save my opinion for the end.
First, health issues. As most people make it, mead is an entirely organic, natural, authentic beverage produced from uncorrupted ingredients. Thusly, we always run the risk that there are harmful organisms present in the finished product. Boiling the honey greatly reduces the chances that a stray bacterium or fungus will contaminate the mix. On the other hand, most people are perfectly happy to eat raw honey with no from of decontamination whatsoever so this concern, while valid, isn't life or death.
Second, consistency. Honey varies in color, density, complexity and quality. Because the boiling process removes virtually everything but the fermentable sugars, each batch of mead produced from similar honeys will be that much more alike. You will have more predictability in your product from year to year and even from batch to batch in the same year.
Third, sediment. If you don't boil the honey, a thick layer of sediment, approximately an inch's worth in a five gallon batch, will collect at the bottom of the brewing vessel. Sediment poses all kinds of problems. When draining or siphoning the mixture you may suck up sediment that will then take days to settle. If you don't filter you will always end up the bit of it in the finished bottles that might make the last swallow unpalatable. The more sediment the more often you will have to rack the batch from one container to another. Worst, if left too long without racking or chemical stabilization, yeast will feed on the sediment producing an unpleasant, burnt/spoiled flavor.
Fourth and most important, clarity. Because boiling removes everything in the honey save the sugars, the components that might cause a batch to be discolored or cloudy are removed ahead of time. Mead from boiled honey is lighter in color and much more transparent than mead from unboiled honey. This gives you a leg up in getting your mead consumed by the uninitiated or bought by the unsure. People are simply more willing to drink things that they can see through. Also, if you were to enter your mead in a brewing contest, clarity is often, though not always, one of the judging criteria.
On the other hand, boiling has it's disadvantages.
First, loss of color. True meade from boiled honey will look like a white wine, whereas the same product made from unboiled honey might have a light amber or orange color that more reflects the nature of the beverage. Hue is also a judging criteria at many festivals. Specifically, the color of the finished product is expected to reflect the color of the varietal of honey.
Second, loss of complexity and varietal. While separating the solids from the rest of the honey, heating also causes the more complex sugars such as maltose and dextrose, which are rich and fruity in flavor, to break down into fructose and glucose, which are basically the same as the white sugar you put in coffee. This leaves you with intense sweetness but costs you subtlety. Heating robs the honey of most of its character and distinction, essentially reducing it to refined sugar. It flattens the taste of the mead, making it much less complex while eliminating many of the flavors specific to varietal honeys.
Third, aging, related to consistency as explained above. Like wine, mead should age, depending on the type, anywhere from four months to three years. While mead made from boiled honey requires less aging compared to an equivalent blend with an unboiled honey, the aging does less. Fewer age dependent compounds are present in the mead. Some people consider this an advantage but most do not. The smoothness, complexity and and robust flavors that come from a properly aged, unboiled, mead cannot be matched in a boiled product. Though the boiled honey mead peaks much faster, if it has an unpleasant sharpness or an aftertaste, those flavors will probably never fully age out.
Personally, I don't boil my honey. Partly, I'm lazy I don't want to take the extra step and I don't want to stink up my kitchen. Much more importantly, though, I'm an adventurer. I make mead as a means of self exploration. I don't like determinism and I'm not trying to produce a commercial product. I much prefer a rich, complex, developed mead to a consistent one. For that matter, if every batch I made came out the same, I probably wouldn't enjoy it nearly so much.
In summation, if you want a consistent, transparent, sterile mead, and you're willing to put in the effort, by all means boil. Don't let any dickhead homebrew snob tell you not to. If you want a less predictable but richer, darker and more adventurous drink don't boil and, likewise tell anyone who says otherwise to perform biologically untenable acts upon themselves.
I've said it before and I'll say it again, there is no right and no wrong way to make mead. I've never understood why but mead people get themselves really worked up over this boiling thing. It's the Catholic/Prodestant, Army/Marines, Camaro/Mustang, GT/UGA, Tastes Great/Less Filling argument of the mead world. Who gives a rat's ass?
Know what you're getting into from the beginning. If you're pleased with your product, make that and drink that but, no matter what you do, do it deliberately.