What It Costs to Think

The other day I changed a light bulb, and then stood there for a minute holding the old one. The bulb I had taken out was an incandescent: sixty watts, around eight hundred and sixty lumens, rated for about a thousand hours. The one going in draws nine and a half watts for the same light and is rated for twenty-five thousand. Same socket, same room, same brightness. A sixth of the power, twenty-five times the life, a few dollars at the hardware store. That is an absurd bargain, and yet it has become nearly invisible. A light bulb is among the oldest and plainest force multipliers we have — it extends the working day, which is to say it extends the usable portion of a life. Every tool in that category works the same way. Glasses correct a lifetime of vision with two pieces of curved glass. A pen, against a quill and an inkwell, is a small object with almost no supply chain behind it and a permanent gain in how quickly a person can think onto paper. These things spread because they gave…