Regularum libri
Ex libro I
Ulpianus, Rules, Book I. Justice is the constant and perpetual desire to give to every one that to which he is entitled. 1The precepts of the law are the following: to live honorably, to injure no one, to give to every one his due. 2The science of the law is the acquaintance with Divine and human affairs, the knowledge of what is just and what is unjust.
The Same, Rules, Book I. Where a slave owned in common is appointed an heir by a stranger, and enters upon the estate by the order of one of his masters; this does not, in the meantime, constitute him the heir of a larger amount than his master is entitled to. If, however, his other masters do not order him to accept the estate, their shares will accrue to him tacitly by operation of law.
The Same, Rules, Book I. The expression “cedere diem” means to begin to owe a sum of money: “venire diem” means the day has come when the money can be collected. When anyone makes an absolute stipulation, the money begins to be due, and the day of payment arrives immediately. When he agrees to pay it at a certain time, the indebtedness begins at once, but the time of payment does not; when he agrees to pay it under a condition, the indebtedness is not incurred, nor is the sum payable, while the condition is pending. 1“Æs alienum” means what we owe to others: “æs suum” is what others owe us. 2Gross negligence is extreme negligence, that is to say, not to know what everybody else knows.