it could very well be 3 to 5...
i remember hearing the term dynamic mean at an introductory rifle building class, conducted at the gunmakers fair, at dixons gun shop in kempton, pa, just west of allentown...a long time ago...
if you define each word literally, dynamic means changing and mean is the same as average...so what we have here is a changing average...whatever that means. i mean...
It has two meanings that I know of. Aristotal applied it to a concept of the middle ground between two extremes. He contended that most values fell in this narrower range. ( Most people or things were middle of the road.) His position was that the variation within this area was the one of importance, and that the most common value always fell in one end of the golden mean or the other. The extremes usually are small and unvarying, so don't really affect anything. (Think politics)
The more important and widespread is referred to as the golden mean (or ratio) in math and art. For the layman it is 5:8 (or 8:5 more rigourisly). Numerically it is 1.625 in useful terms. The actual mathematical number is an indeterminate number of 1.612.......
The most common application is that a picture with these ratios isconsidered the most pleasing, as is the placement of elements in the picture according to this ratio. This applies to both the relation of the object in the picture and the relations between elements.
In math it is one of the most famous theorems in the world. There is a decent quick writeup here:
https://en.wikipedia.org/wiki/Fibonacci_numberA Fibonacci sequence is a series of interrelated numbers increasing in value with a specific relationship. In practical terms it defines most of the complex sequences of shape in nature, almost all of which are considered to have great beauty, form, grace or whatever you want to call it. Chambered Nautilus shells are often presented as an exampled. Spiral galaxies. The seeds in a sunflower head(look closely under a magnifier). I have often thought that sheep horns probably do, giving them a beautiful and desired shape. If you look at the link, you will see at the first the classic example always shown in math books. It is a rectangle of the golden ratio, with subsequently smaller ones fitting in a spiraling pattern of decreasing sizes until they disappear due to size, yet they all fit exactly as they are rotated and inserted.
This is a subject on which entire books have been written and people spend their lives studying.
My take on the theory mentioned by Ed is that it is an offshoot on Aristotle's philosophical approach. Pleasing guns lie between the extremes; who wants a shotgun 8 feet long or 1 foot long. Within the commonly accepted middle range, the desireable range has the bulk of the mass distributed closer to one end than the other. You can place whatever value you want to the balance point, but if nature is a guide, the value could be argued to be 1.612....
Edit------
here is a link discussing it's application to art, which is closer to the original post subject:
https://emptyeasel.com/2009/01/20/a...lden-section-or-golden-mean-for-artists/