(Gaius, Institutes 1. 144-5, 190-1. Tr. Gordon and Robinson. L)
The jurist Gaius (his family name and origin are unknown) was active as a teacher of law in the second century A.D. (150-180). Although he was apparently not one of the influential jurists of his own day, his work as a teacher and writer was much valued in the post-classical period. His Institutes is especially important since it has survived more or less in its original form and, as the basis for Justinian’s Institutes, exerted a tremendous influence on later legal education in Europe.
By the time Gaius was writing, guardianship of women was a mere form, and by the reign of Constantine (306-337), it had vanished altogether.
(144) Where the head of a family has children in his power he is allowed to appoint guardians for them by will. That is, for males while under puberty but for females however old they are, even when they are married. For it was the wish of the old lawyers that women, even those of full age, should be in guardianship as being scatterbrained.  (145) And so if someone appoints a guardian in his will for his son and his daughter and both of them reach puberty, the son ceases to have a guardian but the daughter still continues in guardianship. It is only under the Julian and Papian-Poppaean Acts that women are released from guardianship by the privilege of children. We speak, however, with the exception of the Vestal Virgins, whom even the old lawyers wished to be free of restraint in recognition of their priesthood; this is also provided in the Twelve Tables.
(190) There seems, on the other hand, to have been no very worthwhile reason why women who have reached the age of maturity should be in guardianship; for the argument which is commonly believed, that because they are scatterbrained they are frequently subject to deception and that it was proper for them to be under guardians’ authority, seems to be specious rather than true. For women of full age deal with their own affairs for themselves, and while in certain instances that guardian interposes his authorisation for form’s sake, he is often compelled by the praetor to give authorisation, even against his wishes. (191) For this reason, a woman is not granted any action against her guardian on account of the guardianship; but where guardians are dealing with the affairs of male or female children, when the wards grown up the action on guardianship calls the guardians to account.
14. Translates propter animi levitatem, literally “on account of lightness of the mind”.