By virtue of

Moreouer the perfit beleue of this article, worketh in all true chriſten people, aloue to continue in this vnitie, and afeare to be caſte out of the ſame, and it worketh in them that be ſinners and repentant, great comforte, and conſolacion, to obteine remiſſion of ſinne, by vertue of Chriſtes paſſion, and adminiſtracion of his ſacramentes at the miniſters handes, ordained for that purpoſe, [...]

Source: wiktionary

But in the high Court of Parliament, every Man by virtue of the King's Authority, by Writ under the Great Seal, hath a judicial Place; and ſo conſequently the killing of every of them had been a ſeveral Treaſon, and Crimen læſæ Majeſtatis.

Source: wiktionary

I call that an Inſtitution that hath an efficacie in it for the attaining of ſuch an end by virtue of the Inſtitution, not by virtue of any naturalneſſe that is in the thing. [...] So in preaching the Word, and Eccleſiaſticall cenſures, there is more to be expected, more efficacie to work upon the ſoule, for the ſpirituall man; by virtue of the Inſtitution, then there is in the naturall things that are done there.

Source: wiktionary

[Samuel Keme] became [...] a retainer, if I miſtake not, to the family of Edward Wray of Ricot Eſq, Patron of the ſaid Church, by virtue of his marriage with Elizabeth the dau[ghter] and heir of Francis L[ord] Norris Earl of Berks[hire].

Source: wiktionary