100 561 345 206 113 621 576 131 847 658 131 469
100 369 311 110 500 100 678 488 108 303 399 804

GCHQ would make short work of this. And so will you when I add a hint that will give you the answer. The result is a four-word saying that's oh so true!

Perhaps if I add another hint.....?

adding gives letters...

Got it! (I believe the Talmud says the same thing about brides).

I'm sure you have, TabbyTom. My hints were suggesting the addition process, which results in figures for each three-figure group: 1, 12, 12, 8, 5, 9 ... etc.
Equating these to letters alphabetically gives the phrase:
"All heiresses are beautiful"