This time we have an image from a Finnish book called "young mother's guide" from the 1930s. The caption explains how to carry a small child and finishes with the sentence "The cross means that this is not an acceptable way."
I find this extra piece of explanation absolutely fascinating. In the modern (western) society the usage of crossing out as "no" is so prevalent that it might be hard to notice that this is a meaning that needs to be learned and not an inherent meaning of the sign. But a big (red) "X" is indeed a symbol, not an icon.