The chief source of long close _o_ is the A.S. and Icel. _[=o]_. Ex. _b['o]['o]k_, _fors['o]['o]k_, _d['o]m_, _b['o]ne_ (a boon); from A.S. _b[=o]c_, _fors[=o]c_, _d[=o]m_, and Icel. _b[=o]n_. The distinction between the two kinds of _o_ is perfectly easy to follow, because the sounds are still kept apart in modern English, in which the old open long _o_ is now a close _[=o]_, whilst the old close _[=o]_ is lowered to the sound of _[=u]_ (uu). Easy examples occur in A.S. _b[=a]n_, M.E. _boon_ (baon, b[`o][`o]n), mod. E. _bone_; as contrasted with Icel. _b[=o]n_, M.E. _boon_ (boon, b['o]['o]n), mod. E. _boon_ (buun). In other words, the mod. E. _bone_ was pronounced in M.E. so as to rime with _lawn_; whilst the mod. E. _boon_ was then pronounced so as to rime with _lone_. A few exceptions occur, shewing occasional relaxations of the general rule. They are doubtless due, as Ten Brink suggests, to a paucity of rimes in some particular ending. Thus, when the long _o_ is absolutely final, as in _go_ (gao), _do_ (doo), Chaucer considers these as _permissible_ rimes, and pairs them together freely; and owing to such usage, we even find _agoon_ (agaon) riming with _doon_ (doon) in Troilus, ii. l. 410. But this is the only instance in Troilus of this character; in all other places, the ending _-oon_ relates to the open _o_; the riming words being _alloon_, _anoon_, _atoon_, _boon_ (bone), _foon_ (foes, A.S. _fan_), _goon_, _noon_, _stoon_; to which add _roon_, it rained, _woon_, quantity. In the Cant. Tales, B 3127, we find the rime _d[=o]m_, doom, _h[=o]m_, home; but words in _-[=o]m_ are, of course, extremely scarce, so that there was little else to be done. For a like reason, _sooth_ (sooth) sometimes rimes with _wrooth_ (wraoth), Bk. of the Duchesse, 513, 519, 1189; and _sothe_ (soo.dh[*e]) with _bothe_ (bao.dh[*e]), Sec. Nonnes Tale, G 167; Troil. iv. 1035. With these few exceptions, the rule of distinguishing the two qualities of _o_ is rigorously observed. Thus we find in Troilus, rimes in _-[`o][`o]t_, viz. _hoot_, _noot_, _woot_, _wroot_, A.S. _h[=a]t_, _n[=a]t_, _w[=a]t_, _wr[=a]t_, ii. 890, 1196, iv. 1261. And we find, on the other hand, rimes in _-['o]['o]t_, viz. _foot_, _moot_, _soot_, A.S. _f[=o]t_, _m[=o]t_, _s[=o]t_, iii. 1192. Once more, we find, in the same poem, rimes in _-[`o]te_, viz. _hote_, _note_, _grote_; cf. A.S. _h[=a]te_, adv., A.F. _note_ (Lat. _n[)o]ta_), O. Friesic _gr[=a]ta_; iv. 583. And yet again, there are rimes in _-['o]te_, viz. _bote_, _fote_, _rote_, _sote_, from A.S. _b[=o]t_, _f[=o]t_, Icel. _r[=o]t_, A.S. _sw[=o]te_, adv.; ii. 345, 1378, v. 671, 1245. Every one knows the first rime in the Cant. Tales, that of _sote_, _rote_, (pronounced as mod. E. _soata_, _roata_)[29].