“It is essential to the exercise of such a power that a testator, (a) shall understand the nature of the act and its effects; (b) shall understand the extent of the property of which he is disposing; (c) shall be able to comprehend and appreciate the claims to which he ought to give effect; and, with a view to the latter object, (d) 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.” 198. I should add that the four elements are in my judgment separate requirements, and element (d) is not, as Miss Montgomery at one point submitted, a mere sub-set of element (c). This is shown by the decision in Sharp v Adam itself, where the Court of Appeal upheld the decision of the trial judge that when the testator made the relevant will elements (a), (b) and (c) were satisfied, but element (d) was not: see paragraph [69], where the Court added that the judge could equally well have asked, with reference to the cited passage in Banks v Goodfellow, “whether [the testator’s] human instinct and affections, or his moral sense, had been perverted by mental disease.” 199. The question that the Court of Queen’s Bench had to decide in Banks v Goodfellow, broadly stated, was whether the trial judge had correctly directed the jury in terms which allowed for the existence of testamentary capacity in circumstances where the testator suffered from latent delusions which did not affect his general mental faculties and did not operate on his mind in relation to the testamentary disposition which was challenged. The case was a striking one, because the testator, who made the relevant will in 1863, had been confined for some months as a lunatic in 1841, and had remained from then until his death in 1865 subject to delusions that he was personally molested by a man who had long been dead, and that he was pursued by evil spirits whom he believed to be visibly present. The jury nevertheless held that his 1863 will was valid, and this conclusion was upheld by the Court of Queen’s Bench which held that the judge’s direction to the jury had been correct. 200. The judgment in Banks v Goodfellow is a remarkable one, which repays reading in full. It is, apart from anything else, a masterpiece of English prose. I will not cite from it at length in this judgment, but I should mention two passages which I have found of particular assistance. 201. The first passage is at 568-70 where Sir Alexander Cockburn CJ refers with approval to the decision of the Judicial Committee of the Privy Council in Harwood v Baker (1840) 3Moo.P.C.282 at 291, where Erskine J had delivered the judgment of the Court in the following terms: