I recall reading once upon a time, that the ideal of a Catholic society, expressed sometime in the Middle Ages, was that one-third of the faithful would marry and have families, one-third would remain in the single lay state, and another one-third would go into the priestly or religious life.  I can't recall where I read it, or who said it, but if anyone could direct me to the source, I'd really appreciate it.

Think about this.  If one-third of all people went into the priestly or religious life, assuming an even split between men and women, and if half of those men became priests while the other half became monks, then roughly eight percent of all people would be priests, one priest for every twelve people.  What a fount of sacramental grace that would be!  Masses would be offered more or less continuously throughout waking hours, and weekly or even daily confession would be entirely feasible for anyone.   Assuming further that the monks and nuns were self-supporting (farming and the making of implements needed for daily life, with food and goods sold to the lay faithful), having eleven people providing the temporal support of each priest would insure such support, with money and other means left over.  

Anyone who can furnish a source, I'd be much obliged.  Thanks in advance.

Was it just the middle ages?  I know in my own home parish this was very common.  A family of seven had one priest, four nuns and two got married.  Another family had three or four priests and two nuns but I don't remember how many got married.  Many families had someone who never married or entered religious life.  It was unusual for a family not to have someone enter religion and if they did they had children who became nurses and teachers.  In our city we had both teaching nuns and nursing nuns who ran the hospital so that might account for the interest.

I too would be interested in reading anything outlining the ideal of a Catholic society.

As best I recall, it was from the writings of one of the saints, might even have been Aquinas.  While there were examples such as yours, I doubt it ever played out in society as a whole, I seem to recall it more as an ideal to which to aspire.

I have searched for the quote in vain.  Wish I'd kept it.