s. 214. There is a _difference between a connexion in phonetics and a connexion in grammar_.--Phonetics is a word expressive of the subject-matter of the present chapter. The present chapter determines (amongst other things) the systematic relation of articulate sounds. The word _ph[^o]naeticos_ ([Greek: phonetichos]) signifies _appertaining to articulate sounds_. It is evident that between sounds like _b_ and _v_, _s_ and _z_, there is a connexion in phonetics. Now in the grammar of languages there is often a change, or a permutation of letters: _e.g._, in the words _tooth_, _teeth_, the vowel, in _price_, _prize_, the consonant, is changed. Here there is a connexion in grammar. That the letters most closely allied in phonetics should be most frequently interchanged in grammar, is what, on _[`a] priori_ grounds, we most naturally are led to expect. And that such is _often_ the case, the study of languages tells us. That, however, it is always so, would be a hasty and an erroneous assertion. The Greek language changes _p_ into _f_. Here the connexion in phonetics and the connexion in language closely coincide. The Welsh language changes _p_ into _m_. Here the connexion in phonetics and the connexion in language do _not_ closely coincide. * * * * * {152} CHAPTER III. OF CERTAIN COMBINATIONS OF ARTICULATE SOUNDS. s. 215. Certain combinations of articulate sounds are incapable of being pronounced. The following rule is one that, in the forthcoming pages, will frequently be referred to. _Two (or more) _mutes_, of different degrees of sharpness and flatness, are incapable of coming together in the same syllable._ For instance, _b_, _v_, _d_, _g_, _z_, &c. being flat, and _p_, _f_, _t_, _k_, _s_, &c. being sharp, such combinations as _abt_, _avt_, _apd_, _afd_, _agt_, _akd_, _atz_, _ads_, &c., are unpronounceable. _Spelt_, indeed, they may be; but attempts at pronunciation end in a _change_ of the combination. In this case either the flat letter is changed to its sharp equivalent (_b_ to _p_, _d_ to _t_, &c.) or _vice vers[^a]_ (_p_ to _b_, _t_ to _d_). The combinations _abt_, and _agt_, to be pronounced, must become either _apt_ or _abd_, or else _akt_ or _agd_. For determining which of the two letters shall be changed, in other words, whether it shall be the first that accommodates itself to the second, or the second that accommodates itself to the first, there are no general rules. This is settled by the particular habit of the language in consideration. The word _mutes_ in the second sentence of this section must be dwelt on. It is only with the _mutes_ that there is an impossibility of pronouncing the heterogeneous combinations above mentioned. The liquids and the vowels are flat; but the liquids and vowels, although flat, may be followed by a sharp consonant. If this were not the case, the combinations _ap_, _at_, _alp_, _alt_, &c. would be unpronounceable.