Selection from – Ethics – Part II. On the Nature and Origin of the Mind (Page 10)

Spinoza's Words: (inferring knowledge of the third kind)

After Proposition XLVII as a Note.— Now as all things are in (Deus sive Natura) we can from this knowledge infer many things, which we may adequately know, and we may form that third kind of knowledge the excellence and use of which we shall have occasion to speak in Part V.

Men have not so clear a knowledge of (Deus sive Natura) as they have of general notions, because they are unable to imagine (Deus sive Natura) as they do bodies, and also because they have associated the name God with images of things that they are in the habit of seeing, as indeed they can hardly avoid doing, being, as they are, men, and continually affected by external bodies. Many errors, in truth, can be traced to this head, namely, that we do not apply names to things rightly. For instance, when a man says that the lines drawn from the centre of a circle to its circumference are not equal, he then, at all events, assuredly attaches a meaning to the word circle different from that assigned by mathematicians.

Very many controversies have arisen from the fact, that men do not rightly explain their meaning, or do not rightly interpret the meaning of others.