Consider what effects that might conceivably have practical bearings, – especially in modifying habits or as implying capacities, – you conceive the object of your conception to have. Then your (interpretational) conception of those effects is the whole (meaning of) your conception of the object.
According to Peirce, the words between the dashes and in the parentheses are additions meant to clarify the original maxim.
http://www.commens.org/dictionary/entry/quote-pragmatism-25