_exerceat dictam facultatem, &c._ which prohibits every one from practising physic in London, &c. without licence from the president and college; but extends only to punish those who practise physic in London, _pro delictis suis in non bene [128]exequendo, faciendo & utendo facultate medicinæ_, by fine and imprisonment: so that the censors have not power by the letters patent, and the act, to fine and imprison any for practising physic in London, but only _pro delictis suis in non bene exequendo, &c. sc._ for ill, and not good use and practice of physic. And that was made manifest by five reasons, which were called _vividæ rationes_, because they had their vigour and life from the letters patent, and the act itself; and the best [129]expositor of all letters patent, and acts of Parliament, are the letters patent and the acts of Parliament themselves, by construction, and conferring [130]all the parts of them together, [131]_Optima statuti interpretatrix est (omnibus particulis ejusdem inspectis) ipsum statutum_; and [132]_injustum est nisi tota lege inspecta una aliqua ejus particula proposita judicare vel respondere_. The first reason was, that these two were two absolute, perfect, and distinct clauses, and as parallels, and therefore the one did not extend to the other; for the second begins, _præterea voluit et concessit, &c._ and the branch concerning fine and imprisonment is parcel of the 2d clause. 2. The first clause prohibiting the practice of physic, &c. comprehends four certainties: 1. Certainty of the thing prohibited, _sc._ practice of physic. 2. Certainty of the time, _sc._ practice for one month. 3. Certainty of penalty, _sc._ 5l. 4. Certainty in distribution, _sc._ one moiety to the King, and the other moiety to the college, and this penalty he who practises physic in London incurs, although he practises and uses physic well, and profitable for the body of man; and on this branch the information was exhibited in the King’s Bench. But the clause to punish _delicta in non bene exequendo, &c._ on which branch the case at bar stands, is altogether uncertain, for the hurt which may come thereby may be little or great, _leve vel grave_, excessive or small, &c. and therefore the King and the makers of the act could not, for an offence so uncertain, impose a certainty of the fine, or time of imprisonment, but leave it to the censors to punish such offences, _secundum quantitatem delicti_, which is included in these words, _per fines, amerciamenta, imprisonamenta corporum suorum, et per alias vias rationibiles et congruas_. 2. The harm which accrues by _non bene exequendo, &c._ concerns the body of man; and therefore it is reasonable that the offender should be punished in his body, sc. by imprisonment; but he who practises physic in London in a good manner, although he doth it without licence, yet it is not any prejudice to the body of man. 3. He who practises physic in Lon. doth not offend the