1. Is it possible to compare the value of the portrait-painter's service
with that of the gardener?
2. To call the teacher's work unproductive, and the ditch-digger's work
productive was once usual, but is so no longer; give reasons for either
view.
3. It is usual to call the use of a house for business purposes a
productive use, but its use as a residence an unproductive one. What
reasons are there for and against this?
4. Give a list of material agents that are yielding non-material uses.
5. Give examples of personal services that are most immediately
expressed as gratifications.
NOTE.--The phrase "psychic income," used here for the first
time, expresses a conception long neglected, but essential
to the advancement of psychological economics. The idea has
been recognized in the writings of Edwin Cannan, Irving
Fisher, W. M. Daniels, and perhaps of late by others. It
was discussed by the author in the _Quarterly Journal of
Economics_, Vol. XV, pp. 19-30, especially pp. 25-26, in an
article called "Recent Discussion of the Capital Concept"
(November, 1900).