ALTHOUGH the right of a child to succession and property be established by proving its legitimacy, such right may be suspended or controlled by various incapacities. Idiotism and Lunacy alone require our immediate notice; for though non-age be another impediment to the exercise of a child’s rights, and the fact may sometimes admit of medical elucidation, yet the instances must be rare, and the question will more properly belong to the head of Criminal responsibility; “Idiocy or not is a question triable by jury”[484]; “and sometimes by inspection;” it is distinguished in law from madness[485] & lunacy, being _dementia naturalis vel a nativitate_[486], depending generally on a defective organization, whereas madness and lunacy are _dementia accidentalis_, the former continual, the latter intermittent,[487] both varying in degree, danger, and resistance to cure, yet both capable of cure or palliation by medical treatment, and pre-eminently subjects of medical jurisprudence.[488]. An idiot[489] or natural fool is one that hath had no understanding from his nativity, and is therefore by law, presumed never likely to attain any;[490] 1st. _Blackstone’s Commentaries, c._ 1, _p._ 302. It has been held that an inquisition finding that a person has not had any lucid intervals _per spatium octo annorum_, was a good finding of idiocy; _Prodgers and Phrazier_, 3 _Mod. Rep._ 43, _Skinner’s Reports_, p. 177, and Lord _Donegall’s Case_, 2 _Vesey’s Reports_, p. 408,[491] _contra Prodgers and Phrazier_, 1st _Vernon’s Reports_, p. 12. _see_ 1st _Fonblanque’s Treatise of Equity_, p. 63; but as a person may not have been mentally incapable _a nativitate_, and therefore not an idiot, and yet be affected with madness without lucid intervals, and therefore not legally or logically a lunatic; the better general distinction appears to be, whether the party is _compos_ or _non compos mentis_,[492] but see 1st _Blackstone’s Commentaries_, p. 304, 1st _Fonblanque’s Treatise of Equity_, p. 63, and cases cited there; Lord _Hardwick’s_ Judgment in _Ex parte Barnsley_, 3d _Atkyn’s Reports_, 168,[493] Lord _Eldon’s Judgment in Rigeway and Darwin_, 8th _Vesey’s Reports_, 65; Lord _Erskine’s Judgment in Ex parte Cranmer_; 12th, _Vesey’s Reports_ 445; and _Collinson on Lunatics_. By which authorities it will appear that the jurisdiction of the Court of Chancery[494] over the persons and estates of lunatics extends to those who, being of infirm mind by reason of grief, accident, old age, disease or other cause, are incapable of managing their own affairs.[495]