When the first European settlers in North America were wondering when and how to plant New World cultivars, such as maize, they turned to the local knowledge of the Native American neighbors for help. They were told by Squanto, according to one legend (Chief Massasoit, according to another), to plant corn when the oak leaves were the size of a squirrel's ear. [p. 311]
As a rule of thumb, it was a nearly foolproof formula for avoiding a frost. [p. 312]
- Rules of thumb should generally be interpreted as metaphors.
- Rules of thumb (metaphors) generally come first and the diagrams later. Euclid's geometry, for example, was not so much abstractions directly from nature, but abstractions that could incorporate the geometric rules of thumb already in use (Euclid's Window).
- In using language, following Peirce, we go from the object to a sign (in name only) to an interpretant. In this way we can talk, endlessly it seems, without really knowing what we are talking about.
- Thinking diagrammatically is the effort of going back to the sign and laying out an analogous system that produces that interpretant, and others, from internally generated consequences.