ACONCIO, GIACOMO (1492-1566?), pioneer of religious toleration, was born at Trent, it is said, on the 7th of September 1492. He was one of the Italians like Peter Martyr and Bernardino Ochino who repudiated papal doctrine and ultimately found refuge in England. Like them, his revolt against Romanism took an extremer form than Lutheranism, and after a temporary residence in Switzerland and at Strassburg, he arrived in England soon after Elizabeth's accession. He had studied law and theology, but his profession was that of an engineer, and in this capacity he found employment with the English government. He was granted an annuity of L. 60 on the 27th of February 1560, and letters of naturalization on the 8th of October 1561 (Cal. State Papers, Dom. Ser., Addenda, 1547-1566, p. 495), and was for some time occupied with draining Plumstead marshes, for which object various acts of parliament were passed at this time (Lords' Journals, vol. i., and Commons' Journals, vol. i., passim). In 1564 he was sent to report on the fortifications of Berwick (Cal. St. Pap. For Ser. 1564-1565, passim; Acts P.C., 1558-1570, p. 146); his report is now in the Record Office (C.S.P. For., 1564-1565, No. 512).
But his real importance depends upon his contribution to the history of religious toleration. Before reaching England he had published a treatise on the methods of investigation, De Methodo, hoc est, de recte investigandarum tradendarumque Scientiarum ratione (Basel, 1558, 8vo); and his critical spirit placed him outside all the recognized religious societies of his time. On his arrival in London he had joined the Dutch Reformed Church in Austin Friars, but he was "infected with Anabaptistical and Arian opinions" and was excluded from the sacrament by Grindal, bishop of London. The real nature of his heterodoxy is revealed in his Stratagemata Satanae, published in 1565 and translated into various languages. The "stratagems of Satan" are the dogmatic creeds which rent the Christian church. Aconcio sought to find the common denominator of the various creeds; this was essential doctrine, the rest was immaterial. To arrive at this common basis, he had to reduce dogma to a low level, and his result was generally repudiated. Even Selden applied to Aconcio the remark ubi bene, nil melius; ubi male, nemo pejus. The dedication of such a work to Queen Elizabeth illustrates the tolerance or religious laxity during the early years of her reign. Aconcio found another patron in the earl of Leicester, and died about 1566.
AUTHORITIES.-Gough's Index to Parker Soc. Publ.;
Strype's Grindal, pp. 62, 66; Bayle's Dictionnaire; G.
Tiraboschi, Storia della lett. italiana (Florence,
1805-1813); Osterreichisches Biogr. Lexikon;
Nouvelle biogr. generale; Dict. Nat. Biogr. (A. F. P.)
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)