Geomantic omen with mortar compaction

When I was a teenager, I had a good memory. The book I read is as impressive as the words carved on the slate, and it is not easy to forget. When people reach middle age, their memory declines, and the books they read are as impressive as the words written in chalk, which is easy to erase. By the same token, when you read in old age, you will soon forget when you have an impression.