Since it is the understanding
that sets man above all other animals and enables him to use and dominate them,
it is certainly worth our while to enquire into it.
理解
使人立于所有其他动物之上，并使用和支配他们，
因此，我们当然值得花时间去研究它。
When we are concerned with something about which we have no certain knowledge,
what rules or standards should guide
how confident we allow ourselves to be that our opinions are right?
I hope that this enquiry into the nature of the understanding
will enable me to discover what its powers are how far they reach,
what things they are adequate to deal with, and where they fail us.
If I succeed, that may have the effect of persuading the busy mind of man
to be more cautious in meddling with things that are beyond its powers to understand;
to stop when it is at the extreme end of its tether;
and to be peacefully reconciled to ignorance of things that turn out to be beyond the reach of our capacities.
Before moving on, I must here at the outset ask you to excuse
how frequently you will find me using the word ‘idea’ in this book.
It seems to be the best word to stand for
whatever is the object of the understanding when a man thinks;
I have used it to express whatever is meant by ‘phantasm’, ‘notion’, ‘species’,
or whatever it is that the mind can be employed about in thinking;
and I couldn’t avoid frequently using it.
Nobody, I presume, will deny that there are such ideas in men’s minds;
everyone is conscious of them in himself,
and men’s words and actions will satisfy him that they are in others.
Let us then suppose the mind to be, as we say, white paper,
void of all characters, without any ideas:
How comes it to be furnished?
Whence comes it by that vast store
which the busy and boundless fancy of man has painted on it with an almost endless variety?
Whence has it all the MATERIALS of reason and knowledge?
To this I answer, in one word, from EXPERIENCE.
In that all our knowledge is founded; and from that it ultimately derives itself.
Our observation employed either, about external sensible objects,
or about the internal operations of our minds perceived and reflected on by ourselves,
is that which supplies our understandings with all the MATERIALS of thinking.
These two are the fountains of knowledge,
from whence all the ideas we have, or can naturally have, do spring.
First, our Senses, conversant about particular sensible objects,
do convey into the mind several distinct perceptions of things,
according to those various ways wherein those objects do affect them.
And thus we come by those IDEAS we have of yellow, white, heat, cold, soft, hard, bitter, sweet,
and all those which we call sensible qualities;
which when I say the senses convey into the mind,
I mean, they from external objects convey into the mind what produces there those perceptions.
This great source of most of the ideas we have, depending wholly upon our senses,
and derived by them to the understanding, I call SENSATION.
