Evidence please! Can't wait to see this.
The penal system was originally devised and proposed as an alternative to the then-existing system of corporal punishment for almost every crime under the sun. (Prisons existed merely as holding pens for the short time until the gallows was available.)
You can see this in the alternative name for a prison -- "penitentiary." The idea was that prisoners, given time and solitude to reflect upon the nature of their behavior and its effects upon society, would naturally become "penitent," repent, and return to society a reformed person.
In Wikipedia's words : "For most of history, imprisoning has not been a punishment in itself, but rather a way to confine criminals until corporal or capital punishment was administered. There were prisons used for detention in Jerusalem in Old Testament times.[2] Dungeons were used to hold prisoners; those who were not killed or left to die there often became galley slaves or faced penal transportations. In other cases debtors were often thrown into debtor's prisons, until they paid their jailers enough money in exchange for a limited degree of freedom.
Only in the 19th century, beginning in Britain, did prisons as we know them today become commonplace. The modern prisons system was born in London, as a result of the views of Jeremy Bentham. The notion of prisoners being incarcerated as part of their punishment and not simply as a holding state till trial or hanging, was at the time revolutionary.
The first "modern" prisons of the early 19th Century were sometimes known by the term "penitentiary" (a term still used by some prisons in the USA today or the Dutch "Penitentiare Inrichting/Institution): as the name suggests, the goal of these facilities was that of penance by the prisoners."
What are you talking about? That makes no sense.
You don't send people to a hospital to punish them. You send them to a hospital to treat them, so they become healthy.
The idea behind the "penitentiary system" is that you send people who are morally sick -- as expressed through criminal behavior -- to a location where they can get appropriate treatment and return to society once they become morally healthy.
ETA: dodge noted on how we should enforce law!
No dodge at all. It's not relevant. You can enforce law with mandatory moral treatment just as well as with "punishment,".... and for that matter, you can enforce law with punishment without using prisons (as are done with fines and community service). I didn't feel it necessary to point out the limitations of that rather silly argument about "enforcing the law, " but since you insist....