We review the three key elements to three-level transparency, namely,
the trapped state, dynamical two-photon adiabaticity, and counterintui
tive pulse sequencing. Taken together, they lead to a novel pair of no
nlinear wave equations These equations are exactly integrable and pred
ict that two pulses will evolve into shape invariant pulse forms that
can travel nearly loss-free through the absorbing three-level medium.