Qui testamenta facere possunt et quemadmodum testamenta fiant

Modestinus libro secundo pandectarum.  Testamentum est voluntatis nostrae iusta sententia de eo  quod quis post mortem suam velit. (A will is a lawful expression of our wishes concerning what someone wishes to be done after his death).

Labeo libro primo primo posteriorum a Iavoleno epitomatorum. In eo qui testatur eius temporis quo testamentum facit, integritas mentis, non corporis sanitas exigenda est. (In the case of someone who is making his will, at the time when he makes will, soundness of mind is required, not health of body).

Papianianus libro quarto decimo quaestionum.  Testamenti factio non privati sed publici iuris est. (The making of a will is not a matter of private law but of public law).

Gaius libro secundo institutionum.  Si quaeramus an valeat testamentum in primis animadvertere debemus an is qui fecerit testamentum habuerit testamenti  factionem, deinde si habuerit requiremus an secundum regulas iuris civilis testatus est.  (If we are inquiring whether a will is valid, we ought first of all to consider whether the person who made the will had the power to make a will (testamenti factio) and then if he did have it, we may investigate whether he made a will in accordance with the rules of civil law).

Digestum 28.1.1-4