Today we get trochees and pyrrhic feet slacked like the clouds of New Mexico floating high across the blue canopy of sky. Today we get spondees vaulting like towers, cumulous syllables dwarfing mountains, a vast landscape full of metric vapor.
Substitutions are what Stephen Fry calls spondees, trochees and phyrrhic feet in "An Ode Less Traveled." Our exercise today was to use them.