if he is hindered with respect to his seisin,1 that he have [the same] seisin of the tenement  that his ancestor had, and be recognized as heir, saving to the farmer his term.  If the term has passed, and the farmer attempts to retain the tenement beyond the  term, or transfers it to another, within the term or after it, an assise of novel disseisin  lies for the heir if he so wishes.2 Similarly, the assise of mortdancestor lies for his heir  on the seisin of one within age who dies within age, despite the usufruct which a  farmer or a guardian enjoys, of which the ancestor of the minor did not have seisin on  the day he died, nor the minor while he lived, because though he does not himself  use, he uses through others who are in seisin in his name, for he acts in whose name  an act is done,3 as in the case of those who hold in villeinage, who use and enjoy not  in their own names but in that of their lord, and hence, though another has the  usufruct on the day the ancestor died, he may be said to die seised in his demesne as  of fee, with respect to the free tenement and the fee, not to the use, so that the assise  does not determine the use any more than if the tenement were held in villeinage.  One may hold a tenement in demesne and in fee, and another hold it in service or  with respect to its use. One may hold in fee as regards the service, as a chief lord,  and not in demesne, and another may hold in fee and in demesne and not in service,  as a free tenant; and thus though the tenant sells his tenement to another, the buyer  does not enter the chief lord's fee,4 since he has nothing therein except service,  nothing in demesne except service alone, only into the fee and demesne of the tenant,  nor does the tenant do the chief lord an injuria, though he does him damage,  because he may have his service and distrain his fee no matter who holds it.5 A  tenant may therefore sell his tenement when and to whom he wishes (unless at the  outset a modus is added between them that he may not)6 otherwise the lord would  commit a disseisin to his tenant.
Also as of fee.
 The writ also contains the words as of fee, which the demandant must prove as he  must the other clauses. Thus we must see what may be held in fee and what a fee is.  It is clear that a fee is that which one holds, by virtue of a causa of some kind, to  himself and his heirs,7 whether it is a tenement or a rent, provided that rent is not  taken to mean that which issues out of a chamber,