Here’s a more thorough insight, paraphrased, from the upcoming standalone “Swimming” section of Hébert’s Practical Guide to Physical Education and his Natural Method.
Swimming is considered the most complete of all the exercises.
A complete exercise must at once be hygienic, aesthetic and functional; it must develop absolute strength, as well as sustained strength and develop skill as well as mental energy.
Swimming fulfills all these conditions:
1) Its hygienic effect is intense: swimming activates all the major functions of the organism, particularly respiration; it also cleanses the skin and builds resilience to cold; finally, it is done outdoors. (Translator’s comment: bear in mind that historically speaking, indoor pools were not in existence at the time of Hébert’s authoring of the book).
2) Its action is very effective on the amplification of the thorax and the increase in respiratory capacity. Indeed, in all manners of swimming, the arms are constantly brought beyond the head in the alignment of the trunk, which produces an expansion of the ribs and results in a widening of the thoracic cage. Moreover, the disturbance produced by the body of water and the vigor of the muscular effort force to breathe long and deep.
3) It also has a very intense action on the development of the entire musculature, as it requires various muscular contractions of the arms, legs, trunk and head (neck muscles).
Generally, all these contractions, being very expanded, constitute wonderful exercises for the stretching of the joints and limbs; they are also excellent for the straightening of the spinal column.
4) It requires, to go far and quickly, a perfect coordination of movements and an adequate rhythm.
5) Difficult exercises of diving or water rescue develop dexterity, cold-blood (“even keel”), courage and self-confidence.
6) Finally, all swimming exercises are of no-contest usefulness (meaning, functional, as it’s an important skill you don’t want to overlook, even if you don’t swim daily).
Evidently, to learn something, or simply to perfect one’s technique, it is necessary to work methodically, to have a goal and outline a program.
The swimming session, or “lesson”, just like any training session,must be comprised of a certain amount of varied exercises, performed in a logical order, and must be perfectly regulated when it comes to energy expenditure.
A complete swimming lesson must contain:
1) One or several sudden submersions (of varying height), either head first, or feet first, then coming back to the surface.
2) A regular breast stroke swim, on the stomach, slowly, to begin. This manner of swimming is the best one to realign the spine and any hunching and help acquire or maintain good posture.
3) A swim on the back. Swimming on the back provides rest after a swim of a certain duration on the stomach; this stroke is also indispensable to be adept at during rescues.
4) An underwater “dive”, either starting from an elevation, or at surface level. This exercise consists in staying as long as possible underwater, the body fully submerged.
5) A period of complete rest, called “floating”. No arm or leg movement is to take place during this exercise.
6) One or more “hauls”, using the fastest swimming methods.
7) Finally, finish the lesson with a few slow strokes, on the stomach or the back, in order to restore enough calm in the breathing and circulation, before exiting the water.
Such is the “complete” program of a swim, both hygienic and functional. It’s not just swimming laps, which becomes a specific endeavor, for a sporting event like Swim Meet or a Triathlon, where racing is emphasized, whereas here Hébert is talking about cultivating the skill.