186 MAXIMS OF THE LAW. 



But where there is such a derogatory clause, there can 

 be gathered no such repugnancy : because it seemeth that 

 the testator had a purpose at the making of the first will to 

 make some shew of a new will, which nevertheless his 

 intention was should not take place : but this was answered 

 before ; for if that clause were allowed to be good until a 

 revocation, then would no revocation at all be made, 

 therefore it must needs be void by operation of law at first. 

 Thus much of clausula derogatoria. 



REGULA XX. 



Actus incept us, cujus perfect io pendet ex volant ate partium, 

 revocari potest ; si out em pendet ex voluntate tertiae per 

 sona, vel ex contigenti, non potest. 



IN acts that are fully executed and consummate, the law 

 makes this difference, that if the first parties have put it in 

 the power of a third person, or of a contingency, to give a 

 perfection to their acts, then they have put it out of their 

 own reach and liberty ; therefore there is no reason they 

 should revoke them; but if the consummation depend 

 upon the same consent, which was the inception, then the 

 law accounteth it in vain to restrain them from revoking of 

 it ; for as they may frustrate it by omission and nonfeisance, 

 at a certain time, or in a certain sort or circumstance, so 

 the law permitteth them to dissolve it by an express consent 

 before that time, or without that circumstance. 



Therefore if two exchange land by deed, or without deed, 

 F. N. Br. 36. and neither enter, they may make a revocation or dissolution 

 13 H. 7. 13, O f ne same exchange by mutual consent, so it be by deed, 

 but not by parole ; for as much as the making of an ex 

 change needeth no deed, because it is to be perfected by 

 entry, which is a ceremony notorious in the nature of a 

 livery; but it cannot be dissolved but by deed, because 

 it dischargeth that which is but title. 



F. 36. Eliz. So if I contract with I. D. that if he lay me into my 

 cellar three tuns of wine before Mich, that I will bring into 

 his garner twenty quarters of wheat before Christmas, 

 before either of these days the parties may by assent dis 

 solve the contract ; but after the first day there is a perfec 

 tion given to the contract by action on the one side, and 

 they may make cross releases by deed or parole, but never 

 dissolve the contract ; for there is a difference between dis 

 solving the contract, and release or surrender of the thing 

 contracted for : as if lessee for twenty years make a lease 

 for ten years, and after he take a lease for five years, 



