isomorphismes

—chalked on a sidewalk at my college, years ago

I was reading economics at the time, so it made a lot of sense to cast the preference in terms of isoutility curves. As long as the level curves of 𝓤 over (consumption, leisure) space are sufficiently close to parallel the consumption axis, the above suggestion is rational, even optimal.

In terms of partial derivatives, ∂𝓤 / ∂leisure > ∂𝓤 / ∂consumption at many points in (consumption, leisure) space. More to the point, the directional gradient along the budget constraint points leisureward even at the expense of consumption, for a meaningfully large fraction of the segment.