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.

4018. 'In front of the flocks; and they came on heat as they came to drink' means even to the point of an intense desire in the affection for truth that a joining [to the goods and truths within the natural] might be effected. This is clear from the meaning of 'coming on heat as they came to drink' as an intense desire. The meaning of 'being on heat' as an intense desire is self-evident; and for the meaning of 'coming to drink' as the affection for truth, see immediately above in 4017. The reason why 'in front of the flocks' means that a joining to the truths and goods within the natural might be effected is that this phrase implies seeing and consequent arousal of affection, for this is the manner in which spiritual things are joined to a person. What is more, every implantation of truth or good in a person, as well as every joining of them to him, is effected by means of affection. The truths and goods which a person has learned but for which he has no affection do indeed enter the memory, but they are lodged there as insecurely as a feather on top of a wall which is blown off by the slightest puff of wind.

[2] As regards the things that enter the memory the position is this: Those for which there is no affection pass into the unlit parts of the memory when they enter it, whereas those for which there is affection pass into the light there. Things present in that light are seen and appear clearly and distinctly when any matter of a similar nature is brought up, but not so the things lying around in the unlit parts. Such is the effect that affection belonging to love has. From this it may be seen that all implanting of truth and joining of it to good is effected through affection; and the greater that affection, the stronger the tie joining the two together.

[3] The intense desire of the affection is in this case inmost affection. But truths are not capable of being implanted and joined to good except by means of affections for truth and good, which affections well up from charity towards the neighbour and love to the Lord as their sources. But evils and falsities are implanted by means of affections for evil and falsity, and these affections well up from self-love and love of the world as their sources. This being so, and the subject at this point in the internal sense being the joining of good and truth within the natural man, mention is therefore made here and in what follows of the flock being on heat when they came to drink, by which such considerations are meant.