King, the Classicus Quarter Horse in collected trot.
Lightness is an attitude as much as it is a physical ability. To be light physically requires strength and balance through training whereas to be light mentally is more a result of the relationship established during the training. True classical training does not use forceful methods as it will destroy the relationship with the horse hindering its ability to truly be light. The horse must be encouraged not forced to accept the demands we make on him. Lightness is when the horse mentally and physically accepts the bit (meaning there is a 50/59 relationship with you and the horse), the back is supple and the hindquarters are engaged,
A Lusitano in piaffe
Demure, a warmblood in piaffe