There are two unamiliar words in the Epistle Dedicatory to De Cive. Here’s what they mean.
Meaning, from the OED: “Apt, fit, or suitable.”
this part of philosophy [moral philosophy -mjg] hath suffered the same destiny with the public ways, which lie open to all passengers to traverse up and down: or the same lot with highways and open streets, some for divertisement, and some for business; so that what with the impertinences of some and the altercations of others, those ways have never a seeds†e time, and therefore yield never a harvest. The only reason of which unluckiness should seem to be this; that amongst all the writers of that part of philosophy there is not one that hath used an idoneous principle of tractation. For we may not, as in a circle, begin the handling of a science from what point we please.
a1615 Brieue Cron. Erlis Ross (1850) 5 Quhilk Mark abbot enterit in the monasterie..and fande the said place destitute of idonius personis, ornamentes, etc. 1626 Waterf. Arch. in 10th Rep. Hist. MSS. Comm. App. v. 337 Two idoneows and decent persons shall be..elected wardens of the said yeelde. 1680 BOYLE Produc. Chem. Princ. II. 71 Salt-peter is slowly generated in the earth by gradual..Alterations of some Idoneous Matter. 1726 AYLIFFE Parergon 39 An Ecclesiastical Benefice..ought to be conferr’d on an Idoneous Person. 1822 SYD. SMITH Ess. Wks. (1869) 418 A bitter, bustling, theological Bishop,..the idoneous vehicle of abuse against the Establishment.
The OED notes that this term is “now rare.” Indeed.
when I applied my thoughts to the investigation of natural justice, I was presently advertised from the very word justice, (which signifies a steady will of giving every one his own), that my first enquiry was to be, from whence it proceeded that any man should call anything rather his own, than another man’s. And when I found that this proceeded not from nature, but consent; (for what nature at first laid forth in common, men did afterwards distribute into several impropriations); I was conducted from thence to another inquiry; namely, to what end and upon what impulsives, when all was equally every man’s in common, men did rather think it fitting that every man should have his inclosure.
Meaning, from the OED: “Something appropriated to a private owner; a property. Obs.”
1651 HOBBES Govt. & Soc. Ep. Ded., What Nature at first laid forth in common, men did afterwards distribute into severall Impropriations. 1651 CLEVELAND Poems 7, I will never be your Impropriation.