_And first we crave exceeding pardon in the audacity of the Attempt, humbly acknowledging a work of such concernment unto truth, and difficulty in it self, did well deserve the conjunction of many heads. And surely more advantageous had it been unto Truth, to have fallen into the endeavors of some co-operating advancers, that might have performed it to the life, and added authority thereto; which the privacy of our condition, and unequal abilities cannot expect. Whereby notwithstanding we have not been diverted; nor have our solitary attempts been so discouraged, as to dispair the favourable look of Learning upon our single and unsupported endeavours_. _Nor have we let fall our Pen, upon discouragement of Contradiction, Unbelief and Difficulty of disswasion from radicated beliefs, and points of high prescription, although we are very sensible, how hardly teaching years do learn, what roots old age contracteth unto errors, and how such as are but acorns in our younger brows, grow Oaks in our elder heads, and become inflexible unto the powerfullest arm of reason. Although we have also beheld, what cold requitals others have found in their several redemptions of Truth; and how their ingenuous Enquiries have been dismissed with censure, and obloquie of singularities_. [Sidenote: _Inspection of Urines._] _Some consideration we hope from the course of our Profession, which though it leadeth us into many truths that pass undiscerned by others, yet doth it disturb their Communications, and much interrupt the office of our Pens in their well intended Transmissions. And therefore surely in this work attempts will exceed performances; it being composed by snatches of time, as medical vacations, and the fruitless importunity of_ Uroscopy _would permit us. And therefore also, perhaps it hath not found that regular and constant stile, those infallible experiments and those assured determinations, which the subject sometime requireth, and might be expected from others, whose quiet doors and unmolested hours afford no such distractions. Although whoever shall indifferently perpend the exceeding difficulty, which either the obscurity of the subject, or unavoidable paradoxology must often put upon the Attemptor, he will easily discern, a work of this nature is not to be performed upon one legg; and should smel of oyl, if duly and deservedly handled_.