330 LOGIC : OR TIIE RIGHT USE Or REASON. is sky. So when we look at the colours of the rain -bow, we have a clear idea of the red, the blue, the green in the middle of their several arches, and a distinct idea too, while the eye fixes there ; but when we consider the border of those colours, they so run into one another, that it renders their ideas confused and obscure. So the idea which we have ofour brother, or our friend, whom we see daily, is clear and distinct ; but when the absence of many years has injured the idea, it becomes obscure and confused. Note here, that some of our ideas may be very clear and distinct in one respect, and very obscure and confused in another. So when we speak of a chiliaganum, or figure of a thousand angles, we have a clear and distinct rational idea of the number one thousand angles ; for we can demonstrate various properties concerning it by reason : but the irvctge or sensible idea, which we have of the figure is but confused and obscure ; for we cannot precisely distinguish it by fancy from the image of a figure that has nine hundred angles, or nine hundred and ninety. So when we speak of the infinite divisibility of matter, we always keep in our minds a very clear and distinct idea of division and divisibi- lity. But after we have made a little progress in dividing, and corne to parts that are far too small for the reach of our senses, then our ideas; or sensible images of these little bodies, become obscure and indistinct, and tIre idea of infinite is very obscure, imperfect, and confused. II. Ideas are either vulgar or learned. A vulgar idea represents to us the most obvious and sensible appearances that are contained in the object of them : but a learned idea pene- trates further into the nature, properties, reasons, causes, and effects of things. This is best illustrated by some example. It is a vulgar idea that we have of a rainbow, when we con- ceive a large arch in the clouds, made up of various colours parallel to each other : but it is a learned idea which a philosopher has when he considers it as the various reflections and refractions of sun - beams, in drops of falling rain. So it is a vulgar idea which we have of the colours of solid bodies, when we perceive them to be, as it were, a red, or blue; or green tincture of the surface of those bodies : but it is a philosopical idea when we con- sider the various colours to be nothing else but different sensations excited in us by the variously refracted rays of light, reflected on our eyes, in a different manner, according to the different size, or shape, or situation of the particles of which the surfaces of those bodies are composed. It is a vulgar idea which we have of a watch or clock, when we conceive of it as a pretty instru- ment, made to show us the hour of the day : but it is a learned idea which the watchmaker has of it who knows all the several parts of it, the spring, the balance, the chain, the wheels, their
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