... Dave Lull sends along these two John Derbyshire posts:
Word of the Week - you guessed it. Derbyshire was underwhelmed, but a reader attempted to enlighten him, as noted in Make It Stop.
For what it's worth, here's why the idea is not as trivial as it may seem: The essence of a thing is generally defined as that which makes it what it what it is. But what makes this particular thing what it is in particular is precisely what it does not have in common with anything else. Hence, the mystery of individuation.
Update: Dave alerts me to Derbyshire's "last word" on the subject, which happens to link to what we linked to here.