2144. In the oak-groves of Mamre. That this signifies the quality of the perception, is evident from the representation and signification of "oak-groves," and also from the representation and signification of "Mamre." What "oak-groves" represented and signified in general was shown in volume 1 (n. 1442-1443); and what "the oak-groves of Mamre" represented and signified specifically (n. 1616), namely, perceptions, but such as are human from memory-knowledges [scientific], and from the first rational things thence derived. [2] What perception is, is at this day utterly unknown, because at this day no one has perception like that of the ancients, especially like that of the most ancients; for these latter knew from perception whether a thing was good, and consequently whether it was true. There was an influx into their rational from the Lord through heaven, whereby, when they thought about any holy thing, they instantly perceived whether it was so, or was not so. Such perception afterwards perished with man, when he began to be no longer in heavenly ideas, but solely in worldly and corporeal ones; and in place of it there succeeded conscience, which also is a kind of perception; for to act contrary to conscience and according to conscience is nothing else than to perceive from it whether a thing is so or is not so, or whether it is to be done. [3] But the perception of conscience is not from good that flows in, but it is from the truth that from infancy has been implanted in the rational of men in accordance with the holy of their worship, and which has afterwards been confirmed, for this alone do they in such case believe to be good. Hence it is that conscience is a kind of perception, but from such truth; and when charity and innocence are insinuated into this truth by the Lord, there comes into existence the good of this conscience. From these few observations we can see what perception is. But between perception and conscience there is much difference. (See what is said about perception in volume 1, n. 104, 125, 371, 483, 495, 503, 521, 536, 597, 607, 784, 865, 895, 1121, 1616; about the perception of spirits and angels, n. 202-203, 1008, 1383-1384, 1390-1392, 1394, 1397, 1504; and that the learned do not know what perception is, n. 1387.) [4] As regards the Lord when He lived in the world, all His thought was from Divine perception, because He alone was a Divine and Celestial Man; for He was the only one in whom was Jehovah Himself, from whom was His perception (as to which see also in volume 1, n. 1616, 1791). His perceptions were more and more interior in proportion as He approached more nearly to union with Jehovah. Of what quality His perception was at the time here treated of, may be seen from what has been said about the oak-groves of Mamre in volume 1 (n. 1616); and of what quality it became when He perceived the things that are contained in this chapter, is described in what now follows.