9726. 'And you shall make for it a grating, a network' means the level of sensory perception, which is the last and lowest. This is clear from the meaning of 'a grating, a network' as external sensory perception, thus that which forms for a person the last and lowest level of life; and since this lowest level is meant by the grating it was placed all the way round the altar. Such sensory perception was represented by the grating because it first sifts so to speak and sorts out those things which enter the human mind and present themselves to the understanding and will, namely truths and forms of good. If the sensory perception is composed of good it does not let anything through other than forms of good, and truths derived from good, and rejects evils and the falsities arising from evil. For sensory perception is the actual ability to perceive things which belong to the understanding and to sense those which belong to the will as they exist on outermost levels, an ability that is perfectly fashioned for the affections for those things. The nature of all this may be illustrated by very many things in the body. Everywhere in the outermost parts within the body there are forms that resemble nets and there are so to speak gratings which sort out the things that flow towards them from the world. Those that are suitable are let through because they are desirable, and those that are unsuitable are rejected because they are loathsome. Extremely sensitive systems such as these exist in the stomach. These let through into the blood the suitable juices of the chyle, because these juices are useful and therefore desirable, and reject the unsuitable because they are harmful and therefore loathsome. The situation is similar with sensory perception, which is the last and lowest level of a person's life. But this level with a person has become totally wrecked, the reason why being that it stands right next to and is exposed to the world and is therefore the last to be regenerated, indeed scarcely anyone at the present day is able to be regenerated down to that level. As regards what the level of sensory perception is like with these people, see what has been shown already concerning it in 4009, 5077, 5081, 5084, 5094, 5125, 5128, 5580, 5767, 5774, 6183, 6201, 6310-6318, 6564, 6598, 6612, 6614, 6622, 6624, 6844, 6845, 6948, 6949, 7442, 7645, 7693, 9212, 9216.

Therefore if a person is to see and have an understanding of the truths of faith and the forms of the good of love he must be raised by the Lord above that level to more internal levels. But the sensory perception meant by 'the grating, the network' around the altar is the sensory perception belonging to the Lord's Divine Human, since the altar is representative of the Lord and of the worship of Him that springs from the good of love, 9714.

6314. As it is with light, so it is with the heat that is vital to a person's existence. In no way at all does that vital heat originate in the heat radiated by the sun in the world; rather, it originates in spiritual heat, which is love and radiates from the Lord. This heat is what angels have. Consequently the amount of vital heat a person has is determined by the amount of love he has. His body however is warmed by worldly heat, as is his sensory awareness within it; yet vital heat flows into that worldly heat and imparts life to it. Differences in the purity and intensity of this heat are akin to variations in the clarity of the light. This vital heat is what one should understand by the holy fires mentioned in the Word, and therefore heavenly loves are meant by those fires. But in a contrary sense that worldly heat is what one should understand by the fires of hell, and therefore hellish loves and the desires that go with them are meant when these fires are mentioned in the Word.