Thomas Aquinas,
Summa Theologiae — Question 189 - OF THE ENTRANCE INTO RELIGIOUS LIFE…
“ I answer that, It is not commendable to pass from one religious order to another: both because this frequently gives scandal to those who remain; and because, other things being equal, it is easier to make progress in a religious order to which one is accustomed than in one to which one is not habituated. ”
