Horizontal vs Vertical Development

Horizontal Flow, Vertical Growth 

In this category of individual performance and development, there are two dimensions to consider: Horizontal health and Vertcal growth.

Mihaly Csikszentmihalyi demonstrates a powerful case for Horizontal health as a state of "Flow" that optimally uses the individual's skill level at an optimum level of challenge:

Vertical growth is a notion built on over 100+ yrs of research into adult development, and Lectica.org charts this progress on a psychometric scale: