The physician would find out what the patient needed, then write a specific prescription—and seldom the same prescription for any two patients. For the requirements would always differ.
Or a man might have poor eyesight.
He might go to an optician.
Now, an optician doesn't know much about eyes—he has made a special study of lenses—he merely fits glasses—just as a druggist merely fills prescriptions—neither pretends to diagnose or prescribe.
And an optician is just as likely as not to fit a near-sighted man with far-sighted glasses.
A Truss Fitter Should Know as Much About Rupture as an Oculist About the Eyes
But if the man with poor eyesight goes to an oculist—
The oculist finds out what the trouble is—and what kind of glasses are needed—then prescribes that kind of glasses.
And then the optician fits the man according to the oculist's prescription. Just as a druggist fills a physician's prescription.
Now our method of fitting you by mail is precisely like the physician's method.