In certain recently published philosophical observations by Paolo Sarpi,[20] a nominalist of Occam's school,[21] the following statements are to be found. They are the more notable because standing as they do without any results in Sarpi's thought and being undeveloped in subsequent philosophy, they seem to be not his own invention but a mere repetition of scholastic dicta. "We have certain knowledge both of the existence and of the cause of those things which we understand fully how to create: of those which we know by experience, we know the existence, but not the cause. We can however guess at it, and look simply for a possible cause: but out of many found to be possible we cannot be certain which is the true one. This fact may be seen in descriptions of astronomical theories, and would also be true in the case of a man who saw a clock for the first time. Of the various guesses, that of a man who knew how to make similar objects would be nearest the truth, _e.g._ one who understood the construction of machinery when he saw a different kind of machine: but none the less he will never on that account[22] know for certain. There are then three kinds of knowledge: first, knowledge how to make the object: secondly, experience of it: and thirdly, guessing at possibilities." This thought, then, namely that objects are known by their creator, and that God knows objects because He creates them, seems to have been current in the schools: and this explains the fact of its reappearing in an incidental manner and as an obvious truth in Francesco Sanchez's _Quod nihil scitur_ (1581) where it is declared impossible "_perfecte cognoscere quis quae non creavit; nec Deus creare potuisset nec creata regere quae non perfecte precognovisset_"[23] (that one should know perfectly things which he has not created: nor could God have been able to create nor after creating them to control things which He had not perfectly foreknown).