I love pens. I feel that when I write something down, it is there. No matter what. If I make a mistake, well, I have to live with it. Even if I choose to throw that piece of paper away, my scribblings are still there, for better or for worse.
However, with pencils, you are able to magically erase and rewrite the script that you have written. I understand that erasing is very important, especially when trying to conserve paper. But I bring up the following points in the argument for the pen. Whenever you erase something, the amount of eraser lowers. Think about that next time you want to forget something, you will expend unnecessary resources towards trying to erase that memory. With the same token, there are little fufu's, little eraser bits all over your paper. Those resources that you spent towards erasing that memory or action have suddenly reappear, and they are an annoyance. Lastly, if you look at a paper after it has been erased, there are faint marks still left. It is not impossible, but it is very hard to determine what exactly that you wrote before erasing. Whereas with a pen, you can see everything, mistakes and all.
If you want to look at only a part of your life, be my guest, use pencil.
But my comrades, I urge he who thinks abstractly to look at the entire canvas of life, no matter the errors, for it is a beautiful view.