Lord Coke laid down the rule that a lunatic could not be permitted by plea to show the invalidity of his acts because to do so would be to stultify himself.1 This reasoning would probably prevail nowhere at the present time, and may therefore be disregarded. There are, however, still several theories in regard to the effect of a lunatic's agreement or deed. Most of the cases relate to deeds, but there seems here no distinction in principle between the case of a deed or conveyance of real estate and a contract or sale of personal property, except that if the transaction is wholly executory on both sides, there is less danger of hardship to the sane party, if the lunatic is allowed to treat the agreement as void or voidable, than where the transaction is wholly or partly executed. Decisions, therefore, in regard to deeds, may be taken as establishing a rule of decision for other transactions in the absence of authority to the contrary. The several theories may now be considered.

1 Beverley's Case, 4 Co. Rep. 123 b. 487