Metaphors are a great language tool, because they explain the unknown in terms of the known. But they only work if they resonate in the heart of the writer. So I felt a little understaffed here, loving the metaphor when I came upon it, wanting to work with it, and yet not loving to garden.

Some analogies are so useful that they don’t merely shed light on a concept, they actually become platforms for novel thinking. For example, the metaphor of the brain as a computer has been central to the insights generated by cognitive psychologists during the past fifty years. It’s easier to define how a computer works than to define how the brain works. For this reason it can be fruitful for psychologists to use various, well-understood aspects of a computer—such as memory, buffers, or processors —as inspiration to locate similar functions in the brain.

Good metaphors are “generative.” The psychologist Donald Schon introduced this term to describe metaphors that generate “new perceptions, explanations, and inventions.” Many simple sticky ideas are actually generative metaphors in disguise. For example, Disney calls its employees “cast members.” This metaphor of employees as cast members in a theatrical production is communicated consistently throughout the organization:

• Cast members don’t interview for a job, they audition for a role.

• When they are walking around the park, they are onstage.

• People visiting Disney are guests, not customers.

• Jobs are performances; uniforms are costumes.

Knowing how things are doesn’t make you see them correctly, doesn’t stop you from seeing things incorrectly. Stare at the image as much as you like, it’s all in vain. It will never surrender the truth, not to your naked eyes; you have to go in armed with a straightedge.

At first, I saw it as an enormous change in the man I knew, but that notion did not survive reflection. What presumption is involved in attributing change to him when all that can be said is that I had come to know something about him that I had not known before?

I am reminded of what Einstein said on the death of his friend: He has departed from this strange world a little ahead of me. That means nothing. For us believing physicists, the distinction between past, present and future is only a stubborn illusion.