There is needed a great harmony between the mind, the heart and the body, if you altogether can make such a division.
It is the philosophical harmony, which Plato talked about.
It is obvious that there must be complete harmony, because if there is any inner contradiction, any displacements, frictions, tensions, then there is conflict.
Conflict is in its nature waste of energy; it is the element where the life-urge, or the vitality, is reduced, crumbled, dissolved.
And you need an immensely energy, urge to live, and vitality, in order to be able to go on philosophical discovery. You must be in love with wisdom.
Harmony is in that way necessary so that the mind, the reason, the organism and the heart, in their foundation, are whole, not divided in fragments.
You can see this for yourself, no one need to learn you that.
But how this harmony shall be provided is an entirely other matter.
Complete harmony means that the mind, as well as the organism, must be extremely sensitive. Therefore you must investigate the whole question about the right food, exercises, and a reasonable conduct of life.