Personally I strongly disagree with the author here.

A characteristic of intelligent people is that they know their limits, what they know and what they don't, how quickly or slowly they can learn a new thing and in general have a pretty good idea about their intelligence and how they might be positioned across other intelligent people they know well.

You can't get far if you can't perceive your limits and limitations. This is also where your modesty should come from; the understanding of your boundaries.