[Footnote 158: The Institutes of Caius, (l. ii. tit. ix. x.
p. 144 - 214,) of Justinian, (l. iii. tit. xiv. - xxx. l.
iv. tit. i. - vi.,) and of Theophilus, (p. 616 - 837,)
distinguish four sorts of obligations - aut re, aut verbis,
aut literis aut consensu: but I confess myself partial to my
own division. Note: It is not at all applicable to the Roman
system of contracts, even if I were allowed to be good. -
M.]