The power of images: studies in the history and theory of response by David Freedberg is a very good eye opener if you have a bit of back ground in art and very relevant to this discussion. If you are enjoying this topic I suggest you check it out for one intelligent mans take.
Sometimes it is not about "meanings" at all, but about how you respond to a image. It is easy to memorize or learn what others tell us this or that image/icon means. But rather then only relying on meanings look at how they or you respond to the card or image and ask yourself why.
I have a tendency of tracing meanings forward or backward through time and trying to understand why these changes came about. I rarely find out definitively why, but I have fun tracing them and putting my spin on "why" and it helps me understand the progression of a card. Most changes are big jumps. They are not often subtle.
Meanings change with time, wars, and ideologies. Meanings change across cultures within the same era. There are so few cross cultural/time iconic images that we can count them easily.
I wonder how many people outside our circle and those of scholars who studies include these things know what pomegranate, corn, wheat, sickles, lily's red roses, dogs or water etc, traditionally represent or their meanings? Most of us here see these things as obvious. They are not.