An affirmative will produces no effect without a negative.
Placitum debet esse verum, sufficiens, certum, simplex, et brevi congruens, et præcedentibus constans, et ordinem spectans.
A will ought to be true, sufficient, clear, simple, and agreeing with the brief, and consisting with preceding ones, and having regard to order.
Placitum mendax non est placitum.
A lying will, is not a will.
Placitum nemo cassabit nisi melius dando.
Nobody can make void a will, unless by giving what is better.
Plus cautionis in re est, quam in persona.
There is more security in property, than in a person.
Plus enim valet quod agitur quam quod similate concipitur.