[GAIUS libro singulari de casibus. ] §38.1.49.prDuorum libertus potest aliquo casu singulis diuersas operas uno tempore in solidum edere, ueluti si librarius sit et alii patrono librorum scribendorum operas edat, alter uero peregre cum suis proficiscens operas custodiae domus ei indixerit: nihil enim uetat, dum custodit domum, libros scribere.
[GAIUS, On Singular Cases, in one book.] A freedman of two patrons can in a certain case render different services to each of them at the same time in full, as for instance if he is a copyist and renders to one patron the services of copying books, while the other, departing abroad with his household, has enjoined upon him the services of guarding his house; for nothing prevents him from writing books while he is guarding the house.
hoc ita Neratius libris membranarum scripsit.
Neratius wrote this in his Books on Parchments.