Testament, as it may be called, differed in its primitive form from a modern will. As it amounted to a conveyance out-and-out of the Testator's estate, it was not revocable. There could be no new exercise of a power which had been exhausted.
Again, it was not secret. The Familiæ Emptor, being himself the Heir, knew exactly what his rights were, and was aware that he was irreversibly entitled to the inheritance; a knowledge which the violences inseparable from the best-ordered ancient society rendered extremely dangerous. But perhaps the most surprising consequence of this relation of Testaments to Conveyances was the immediate vesting of the inheritance in the Heir. This has seemed so incredible to not a few civilians, that they have spoken of the Testator's estate as vesting conditionally on the Testator's death, or as granted to him from a time uncertain, i. e. the death of the grantor. But down to the latest period of Roman jurisprudence there were a certain class of transactions which never admitted of being directly modified by a condition, or of being limited to or from a point of time. In technical language they did not admit conditio or dies. Mancipation was one of them, and therefore, strange as it may seem, we are forced to conclude that the primitive Roman Will took effect at once, even though the Testator survived his act of Testation. It is indeed likely that Roman citizens originally
