impossibilium nùlla obligàtio est - there is no obligation to do the impossible.
hòminum càusa jus constitutum est - law exists for the benefit of humanity.
ibi jus, ibi (ubi) remèdium - where there is a law, there is a means of protection (the law is where there is a means of its protection).
gràtis dictum - a statement made without a specific purpose.