INERTIA. 605 INFALLIBILITY. ing wheel, oto. It is noticed that the intensity of the sensation depends botli on the material body itself and on the rate at whieh its motion is changed. Similarly, if the motion of the body is slopjied by some inanimate object, the effect on the latter is proportional to the rate of de- crease and varies with the body stopped; e.g. if a nnjving body meets a spinil spring and com- ]iresses it until it is brought to rest. If two mov- ing bodies are brought to rest by a given spring in the same time and produce the same amount of compression, they may be said to have the .■^ame inertia. (On this definition is based the system for measuring quantities of matter, q.v.). If it fakes longer to bring the first body to rest, it is said to have the greater inertia, it is be- lieved that, if there were nothing external to the moving body aflTecting it, it would continue to maintain its motion unaltered forever. Galileo was the first to advance this idea ; and it is now assumed as one of the principles of mechanics. On the other hand, if there is some external ac- tion on the body it takes time to produce a change in its motion, and the change produced in a given time will vary inversely as the inertia ; or, to ])roduce a given change in motion, the ex- ternal action rci|uired varies directly as the in- eitia. It is to New Ion that i' owe our ideas of inertia as a measurable fundamental property of matter. Up to his time weight was the only ])ro|)ci-(y of matver used as a measure of the Viuaiil ity of matter.' INESCUTCHEON ( in + escutcheon, from OF. escusfson, escui^on, Fr. ecusson, escutcheon, from OF. cscut, escu, Fr. fcii, shield, from Lat. scut^im, shield). In heraldrj' (q.v.), a single shield borne as a charge. INES DE CASTRO, e'nes de kii'strS. See Castro, Ike/, he. INESILLA DE CANTABILLA, e'na-selya dS kan'ta-re'lya. In Le Sage's (S'll Bias, a char- acter who retained the jiower of charming men during the whole of a. long life. INEXPIABLE WAR, The. A war of exter- mination waged by Carthage against her im- paid mercenaries in B.C. 241-2HS, The sceiies of this war are pictured in Flaubert's Halamrnhd. I'NEZ, Hpan. pron. e'nAth, Donna. In Byron's Don Juan, the mother of Don Juan. INFALLIBILITY (from ML. infaUihilis. in- fallible, from in-, not + fallibilis, fallible, from fallere, to deceive, Gk. a(t>iWei.v , sphallein, to overthrow, AS. fiallan, OHG. falhin, Cer. fallen, Eng. fall). The immunity from error, in all that regards failh and morals, which is claimed by the Roman Catholic Church, and. at least as regards the past, by the Greek Church, as rei)resen1ed in tile decrees of the councils which the latter looks upon as ecumenical. The latter claim, how- ever, which does not go beyond that of inerrancy, or actual exemption from error up to (he present time, differs widely from that of infallibility as put forward by the Roman Church, which in- volves not alone an actual historical immunity from error, but also such a positive and abiding assistance by the Spirit of God as will at all times both protect against (he possibility of error, and iruide and direct in (he faithful (cach- ing of all necessary truth. The infallibility claimed by the Koman Church is thus of two kinds, pas- sive and active — the first (JIatt. xvi. IS), in irtue of which the Church never can receive or c'lihrace any erroneous doctrine, no matter by whom proposed; the second, in virtue of which bile is charged with the function (Matt, xxviii. 19; Mark xvi. 15; Ejihes. iv. 11-10) of perma- nently tf'aching to the world the essential truths of God, of actively resisting every access of error, and of authoritatively deciding evcu'y controversy by which the oneness of belief among the faith- ful may be endangered. Catholics regard this gift as a natural and necessary accompaniment of the authority in the matters of faith with which they believe the Church to be invested, and which, if not guided in ito exercise by such infallible as- sist<uiee, would be but a false light, and an at- tractive but dmgenms delusion. They have al- ways agreed that the body of bishops tliroughout the Church, acting in connuon with the I'ope, con- stitute the most perfect organ of the infallibility of the Church ; and hence, that when they unite in any way, whether as assembled in a general council or .separated in place, their judgment is infallible. Thus, if a doctrinal decree were ad- dressed ofTicially by the Pope to the whole Church, and either expressly confirmed or tacitly accepted by the bishops, this decree was held to be infalli- ble. In like manner, if a doctrinal decree, ema- nating even from a local council, as that of a national or even a provincial Churcli. should be universally accepted by the Pope and the bishops, that decree also was held to be infallilile. In a word, wherever there is found the tinited judg- r.ient of the Pope and the bishops, all agreed in accepting it as the infallible judgment of the Church. P>ut should the Pope alone judge with- out the bishops, there arose the well-knov^l dis- pute of the Gallican and Ultramontane divines; the latter alRrming. the former denying, the Papal judgment to be infallible, but all agree- ing that it was not binding as an article of Catholic faith so long as it had not received the assent of the body of (he bishops. The for- mal definition of Papal infallibility as de fide dates from the Vatican Council of 1870. The minority of bishops who opposed the decree did so, as a rule, not because they disbelieved the doctrine, but because they considered its im- position as a necessary article of faith inexpedi- ent. As ftn-nially declared, the definition is that (he doctrinal decrees of the Pope teaching ex cathedra — that is, when in discharge of the office of pastor and doctor of all Christians, by virtue of his supreme apostolic authority, he defines a doctrine regarding failh and morals to be held by the universal (^'liurch — are to be ac- cepted as possessing the same infallibility which attaches to the teaching of the Church. See Coi'NCII,. On the matter of subjects to which the gift of infiillibility extends, Catholics are agreed iu one principle, that it embraces all those sub jects, and those only, whieh are necessary for the maintenance of divine truth in the Church. Hence, presupposing divine revelation, either written or oral, it embraces all questions of faith and morality, all stibjects of general discipline, so far at least as to preclude the introduction, by authority of (he C^hurch, of any discipline which should be injurious (o fai(h or (o morality. On (he o(her hand, it does not embrace qucs- (ions of science, or maf(ers of fac(, or abstract o|iinions tinconnec(ed with religion. Thus the popular misconception that the decision in the case of Galileo beal-s on the question of this
