It is a strange idea I think. Sometimes when people write or say that they don't do, or their horse doesn't do dressage or like dressage, I'm puzzled by this thinking.
I think, conceptually, that all horse training has the potential (when done thoughtfully with care and kindness ) to be "Dressage" - no matter what discipline we are doing, what obstacle we are negotiating, inside or outside the arena, what clothes or tack we are wearing, or mindset we are thinking - if we are working on improving a horse's health and longevity. By giving respect to its physical and emotional nature, educating ourselves on ethology, anatomy and biomechanics, and improving how to communicate techniques - we are involved in the practice of dressage.
To me Classical Dressage - could be defined as training that works for the benefit of the horse. ie with respect for its nature, its mental and physical needs and its natural balance with or without a rider, a gradual process of thoughtful gymnastic development to ensure a long healthy happy life. To help it find a comfortable natural balance with a rider.
Dressage and collection, with these ideas, is a question of balance. Balance, together with the basics of impulsion and relaxation: ie. a ready and willing mobility both laterally and longitudinally, in any direction, at any moment, and without tension. In order for collection in balance - the head, neck and shoulders raised and lightened, the quarters lowered and taking more weight. (Piaffe being the ultimate example). What is this training, if not practical, effective working dressage for any field? Can a horse effectively perform any discipline if it is not trained to an appropriate balance for the job at hand?
This is a photo of me at 22 on Citadel, an very kind Arab stallion I rode through many happy miles of bush trails before I knew anything about dressage - and at this stage i would probably have thought that I didn't 'do' dressage, simply because I knew nothing of its benefits and had only my misguided assumptions from pictures I saw at that time.
When did you discover the joy of dressage?