John F. Sowa gave a keynote on “Language, Ontology, and the Semantic Web” at ESWC this year. The slides are online.

I love slide 55, “Advice From Two Logicians and a Poet”:

Alfred North Whitehead:

Human knowledge is a process of approximation. In the focus of experience, there is comparative clarity. But the discrimination of this clarity leads into the penumbral background. There are always questions left over. The problem is to discriminate exactly what we know vaguely.

Charles Sanders Peirce:

It is easy to speak with precision upon a general theme. Only, one must commonly surrender all ambition to be certain. It is equally easy to be certain. One has only to be sufficiently vague. It is not so difficult to be pretty precise and fairly certain at once about a very narrow subject.

Alfred North Whitehead:

We must be systematic, but we should keep our systems open.

Robert Frost:

I’ve often said that every poem solves something for me in life. I go so far as to say that every poem is a momentary stay against the confusion of the world… We rise out of disorder into order. And the poems I make are little bits of order.