Why Volume Four? The easy answer is because I cannot shut up. A more complex response is that as the years pass, I realize that some of what I talked about is outdated and I've found a better way to do this or that. Or I have additional experiences that cause me to rethink my previous thoughts such as Vol I mentioned condom-canteens and in Vol III I revisited that thought with more info, but still no experiences as I still think that the idea is disgusting. Also as time goes on, new experiences provide new thoughts on new topics and I purchase or am gifted new gear and wish to share my thoughts and experiences on the new junk. Plus I cannot shut up.