The Gray Mouser differs from the Catzilla brothers in one very important way: he's not much of a climber. He'll scramble up onto a sofa or bed if he's invited, but he doesn't jump and he certainly doesn't come close to Whitey's acrobatics.
Perhaps because he himself doesn't climb much, he doesn't seem to think in three dimensions. He'll let the boys get much closer vertically than horizontally. This two-dimensional thinking clearly manifested itself this afternoon.
The Mouser was lounging on the floor in the library, between the end table and the library cat tower. Whitey was sitting on the end table, more or less directly above the Mouser. He reached a paw carefully downward, but retreated when the Mouser glared at him. So he adjusted his position, judged the distance, and leaped from the end table to the top of the cat tower, a straight line distance of more than four feet. The Mouser didn't flinch, even when the tower rocked and rattled the window blinds.
I was especially impressed by Whitey's respect for the air rights over the Mouser. He could have cut the distance in half by jumping straight across, from the end table to a lower level of the tower, but that would have carried him through the Mouser's personal bubble. Instead he went for the much more difficult vertical leap. Clearly, our SpiderCat still has it.