At the time of writing, the basic test for determining whether a testator has sufficient capacity to make a valid will derives from Banks v Goodfellow (1870) L.R. 5 Q.B. 549. Cockburn C.J. held it essential that a competent testator: shall understand the nature of the act and its effects; shall understand the extent of the property of which he is disposing; shall be able to comprehend and appreciate the claims to which he ought to give effect; and, with a view to the latter object, that no disorder of the mind shall poison his affections, pervert his sense of right, or prevent the exercise of his natural faculties—that no insane delusion shall influence his will in disposing of his property and bring about a disposal of it which, if the mind had been sound, would not have been made (at 565).