“Neither Steve Breyer nor Ruth Ginsburg has much of a purchase on Tony Kennedy’s mind.”

That's actually the most embarrassing sentence in Larry Tribe's letter to Obama about who to nominate to the Supreme Court.

I love the use of the noun "purchase," meaning, not something you buy, but "A means of increasing power or influence" or "An advantage that is used in exerting one's power." That's the 5th definition of the noun in the 3d edition of the American Heritage Dictionary. Here are some other, related definitions:

2. A grip applied manually or mechanically to move something or prevent it from slipping.

3. A device, such as a tackle or lever, used to obtain mechanical advantage.

4. A position, as of a lever or one's feet, affording a means to move or secure a weight.

You get the idea of the image Tribe had of Kennedy's brain? If you read the whole letter — PDF — you'll see that Tribe thought Justice Souter had "purchase," and he was worried that without Souter, Kennedy would roll toward the "Roberts/Alito/Scalia/Thomos wing of the Court." He thought Elena Kagan — and not Sonia Sotomayor — would operate — as a tackle or lever? — to move "Tony Kennedy's mind."

Kagan, Tribe said, had a way of "gently but firmly persuading a bunch of prima donnas to see things her way in case after case." Of course, he was referring to the prima donna professors at Harvard Law School, and mainly talking about new faculty appointments, which is quite different from persuading Supreme Court Justices about interpretations of law. It's one thing to build a law school community where professors can spout diverse ideologies and still feel like it's a happy, functioning institution. It's quite another to amass votes for a legal proposition that produces an outcome in a case and binds all the courts in the United States.

And if the target of a light touch knows that the most powerful man in the world has selected that approach to prying his brain into a particular political direction, that target ought to become highly vigilant and not get played.

... I think it's clear that a Justice Kagan would be a much more formidable match for Justice Scalia than Justice Breyer has been... in the kinds of public settings in which it has been all to easy for Scalia to make his rigid and unrealistic formalism seem synonymous with the rule of law and to make Breyer's pragmatism seem mushy and unconstrained by comparison.

Tribe says Kagan will be "simultaneously progressive yet principled, pragmatic and yet constrained." That sounds like pragmatism. How does it not "seem mushy" like Breyer's pragmatism? Because it's asserted to be "constrained," while Breyer's pragmatism "seem[s]... unconstrained"? Because it's progressive — steadily aimed in one direction and not more subtly varied?

I'm sure Justice Kennedy doesn't need to be tipped off to this political scheme to clamber over the crusty crags of the convolutions of his brain. But Tribe's letter is amusing reading nonetheless.