There are few things more important in the outdoors than your clothing. Humans have, unlike other members of the animal kingdom, not become terribly adapted to life north of the tropics. Even the furriest of us are unlikely to survive a night exposed in the frozen sub arctic forest. Thus humans adapted using our superior intellect and created clothing to keep us warm, dry and protected. Clothing is our mobile shelter, keeping us alive.
The funny thing is... or maybe not so funny depending on your point of view and circumstance, that clothing suitable for wilderness use is regressing. Even a mountain man or plains Indian of two hundred years ago was quite likely more suitably dressed than a dapper model from North Face or Columbia. Humans have developed such a marvelous system of transportation and living arrangement that very few of us are exposed to the elements for very long and if exposed we are at recreation and leisure- not exposed to the typical rigors of bush living.
We have some marvelous textiles available, GoreTex, PacLite among others. The so called "waterproof breathable" fabrics seem to appeal to the surburban. Lightweight and generally affordable these adorn ever growing numbers of humans on a daily basis. While poly based clothing may be supremely comfortable for walking from the car to the mall or riding the downtown bus on a rainy day it is not particularly attractive to the serious wilderness user.
Ever see a cowboy in a Gore Tex coat? Or a construction worker? Maybe a logger?
I doubt it and here's why. Gore Tex type materials are pretty dependent on cleanliness to maintain their water resistance. A good coating of woods grunge and that garment will wick water like a sponge. Good rain gear is generally rubber or heavy poly coated cotton. Helly Hansen and Grundens make good examples of this. A popular outiftter on the Aleutian Island of Adak will refuse to take any client not appropriately attired in rubber gear- Gore Tex need not apply. My time in the Aleutians certainly hold true. A torrent blowing at 60mph will make waterproof a relative term- my Hellys never let me down.
The other shortcoming of most of this gear is its ability to not burn. It doesn't burn easily but it does melt readily. Several years ago I was camping in my new "wonder coat". A brief moment of inattention and a good size piece of the sleeve had melted away leaving a large hole. I doubt my decade old Carhartt would have even smelled of smoke after such a brief exposure to flame. Don't get me wrong, cotton canvas, wool and the like will burn- but not readily and it certainly doesn't melt from a distance. For the serious woodsbum exposure to flame is a certainty on a daily basis.
For cold weather clothing wool is wonderful and long wearing. Down also makes a pretty good insulator for deep dry cold but its typically wrapped in polyester these days. The new synthetic pile clothes that are so popular are usually warm enough but the pile tends to collapse with wear and even a good appearing garment can lose a lot of insulating ability. Then there is the melting factor. Cotton canvas also makes a good garment as heavy canvas is nearly windproof and almost bulletproof. I tend to wear canvas when I'm going to be in brush. It's true that cotton- even canvas will not insulate when wet and wool is a better choice for a cold, wet environment.