Our knowledge springs from two fundamental sources of the mind; the first is the capacity of receiving representations (receptivity for impressions), the second is the power of knowing an object through these representations (spontaneity [in the production] of concepts).
Too much openness and you accept every notion, idea, and hypothesis-which is tantamount to knowing nothing. Too much skepticism-especially rejection of new ideas before they are adequately tested-and you're not only unpleasantly grumpy, but also closed to the advance of science. A judicious mix is what we need.
Not to know what has been transacted in former times is to be always a child. If no use is made of the labors of past ages, the world must remain always in the infancy of knowledge.
It is commonly observed that a sudden wealth, like a prize drawn in a lottery or a large bequest to a poor family, does not permanently enrich. They have served no apprenticeship to wealth, and with the rapid wealth come rapid claims which they do not know how to deny, and the treasure is quickly dissipated.
It is rightly laid down that 'true knowledge is knowledge by causes'. Also the establishment of four causes is not bad: material, formal, efficient and final.
Depend upon it there comes a time when for every addition of knowledge you forget something that you knew before. It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones.
The reasons for which 'this' world has been characterized as 'apparent' are the very reasons which indicate its reality; any other kind of reality is absolutely indemonstrable.
We have arranged for ourselves a world in which we can live - by positing bodies, lines, planes, causes and effects, motion and rest, form and content; without these articles of faith nobody could now endure life. But that does not prove them. Life is no argument. The conditions of life might include error.