OBS. 41.—­Idioms, or peculiarities of expression, are never to be approved or valued, but according to their convenience, utility, or elegance.  By this rule, some phrases that are not positively barbarous, may yet be ungrammatical, and a construction that is sometimes allowable, may yet be quite unworthy to be made or reckoned, “the common mode of expression.”  Thus, in Latin, the infinitive verb is occasionally put for a noun, and taken to signify a property possessed; as, “Tuum scire, [thy to know,] the same as tua scientia, thy knowledge.  Pers.”—­Adam’s Gram., p. 153.  So, in English, the participle in ing is often taken substantively, when it does not actually become a substantive or noun; as, “Thy knowing this,”—­“Our doing so.”—­West.  Such forms of speech, because they are idiomatical, seldom admit of any literal translation, and are never naturalized by any transfer from one language or dialect into an other; nor is it proper for grammarians to justify them, in vernacular speech, except as figures or anomalies that ought not to be generally imitated.  It cannot be truly affirmed, that the genius of our language ever requires that participles, as such, should assume the relations of a noun, or govern the possessive case; nor, on the other hand, can it be truly denied, that very excellent and learned writers do sometimes make use of such phraseology.  Without disrespect to the many users and approvers of these anomalies, I set down for bad English every mixed construction of the participle, for which the language can furnish an equivalent expression that is more simple and more elegant.  The extent to which these comparative barbarisms now abound in English books, and the ridiculous fondness for them, which has been shown by some writers on English grammar, in stead of amounting to any argument in their favour, are in fact, plain proofs of the necessity of an endeavour to arrest so obvious and so pernicious an innovation.

OBS. 42.—­A late author observes as follows:  “That the English gerund, participle, or verbal noun, in ing, has both an active and a passive signification, there can be little doubt.[424] Whether the Latin gerund has precisely a similar import, or whether it is only active, it may be difficult, and, indeed, after all, it is not of much moment, to ascertain.”—­Grant’s Latin Gram., p. 234.  The gerund in Latin most commonly governs the case of its own verb, as does the active participle, both in Latin and English:  as, “Efferor studio patres vestros videndi.  Cic. de sen. 23.”—­Lily’s Gram., p. 96.  That is, “I am transported, with a desire of seeing your fathers.”  But sometimes we find the gerund taken substantively and made to govern the genitive.  Or,—­to adopt the language of an old grammarian:—­“Interdum non invenuste additur gerundiis in di etiam genitivus pluralis:  ut, ’Quum illorum videndi gratia me in forum contulissem.’—­’Novarum