IthinkImaylaydownthat，whereverwehaveanyknowledgeofabodyofAryancustom，eitheranteriortoorbutslightlyaffectedbytheRomanEmpire，itwillbefoundtoexhibitsomestrongpointsofresemblancetotheinstitutionswhicharethebasisoftheBrehonlaw。Thedepthtowhichtheempirehasstampeditselfonthepoliticalarrangementsofthemodernworldhasbeenillustratedoflateyearswithmuchlearning；butI
repeatmyassertionthatthegreatdifferencebetweentheRomanEmpireandallothersovereigntiesoftheancientworldlayintheactivityofitslegislation，throughtheEdictsofthePraetorandtheConstitutionoftheEmperors。Formanyraces，itactuallyrepealedtheircustomsandreplacedthembynewones。
Forothers，theresultsofitslegislationmixedthemselvesindistinguishablywiththeirlaw。Withothers，itintroducedorimmenselystimulatedthehabitoflegislation；andthisisoneofthewaysinwhichithasinfluencedthestubbornbodyofGermaniccustomprevailinginGreatBritain。ButwherevertheinstitutionsofanyAryanracehavebeenuntouchedbyit，orslightlytouchedbyit，thecommonbasisofAryanusageisperfectlydiscernible；
andthusitisthattheseBrehonlaw-tractsenableustoconnecttheracesattheeasternandwesternextremitiesofalaterAryanworld，theHindoosandtheIrish。
TheLectureswhichfollowwillhelp，Itrust，toshowwhatusethestudentofcomparativejurisprudencemaymakeofthisnoveladditiontoourknowledgeofancientlaw。Meantime，thereissomeinterestincontrastingtheviewofitsnature，origin，andgrowth，whichweareobligedtotakehere，withthattowhichtheancientIrishpractitionersoccasionallystrovehardtogivecurrency。TheSenchusMor，theGreatBookoftheAncientLaw，wasdoubtlessamostpreciouspossessionofthelaw-schoolorfamilytowhichitbelonged；anditsownershavejoinedittoaprefaceinwhichasemi-divineauthorshipisboldlyclaimedforit。