I have an unusual tool that I bought over 50 years ago and it has NEVER been used. When I was in junior high school I needed to buy some drafting tools for a mechanical drawing class. The sales clerk helped me assemble everything I would need; the drawing board, T-square, triangles, mechanical pencils and, finally, one of those three-sided, twelve-inch rulers - the architectural scale. Most of them that he showed me were made of white plastic but I picked out a nice looking wooden one from the display cabinet and said, “I’ll take that one.”
“No, you need one of these,” he said as he kept pushing a white plastic one into my hand. But I liked the one I picked and I was going to buy it. He tried several times to tell me that what I had was an engineer's scale.
Engineer; architect, “Yeah, whatever!” I replied sarcastically. I didn’t know why he was arguing with me over semantics. After all, he was just a dumb sales clerk but I was the drafting student and I knew that those three-sided rulers where architectural scales. He finally let me have it my way and he rang up my order.
When I got home and laid out my tools, I mounted some drafting paper to my new drawing board and began to draw. That's when I realized that an engineering scale is NOT an architectural scale. Nothing on that scale was useable to me. It cost me several dollars to learn, the hard way, that I don’t know everything.
Sometimes people who have been “around the block’ a few more times try to warn us or save us some grief. But we ignore them and insist on doing our own thing. Or someone tries to tell us something and we think we know better so we don’t listen. And when that happens, those people will often just quietly back off and let us suffer the consequences of our foolishness.