The color green is almost exclusively used in connection with plants in the Bible, and the meaning is closely connected to the meaning of plants as well. Plants, in general, represent facts, knowledge that we can gather from the world. Green plants are ones that are alive and growing. Since life represents love and goodness, it makes sense that green plants are facts that have the potential for good use. It also indicates that they are the kinds of things we learn through directly through our senses, since to identify green plants we need to actually see the greenness.

(References: Apocalypse Explained 507; Apocalypse Revealed 426; Arcana Coelestia 7691)

10028. 'And shall pour out all the blood at the base of the altar' means the whole of Divine Truth present on the level of sensory perception, which is the lowest level of life in a person. This is clear from the meaning of 'the blood' as Divine Truth springing from the Lord's Divine Good, dealt with just above in 10026; and from the meaning of 'the base of the altar' as the level of sensory perception, which is the lowest level of life in a person. 'The base of the altar' has this meaning because the altar was representative of the Lord's Divine Human, and therefore the base of it means that which forms the lowest level of life in the human being, and that which forms the lowest level of life in the human being is called outward sensory perception, which is what is meant here. The altar was the chief representative of the Lord's Divine Human, see 9388, 9389, 9714, 9964, 'the base', it is self-evident, being the lowest level of it. As regards this level in the human being, that it is outward sensory perception, and as regards the nature of it, see 9212, 9216, 9996.

[2] The implications of all this must be stated briefly. When a person is being purified he first of all learns the kinds of truths that someone who thinks on the sensory level can grasp; these are truths such as exist in the literal sense of the Word. Afterwards he learns more internal truths such as are gathered from the Word by those who have enlightenment; for these gather its inner meaning from various places where the literal sense there is explained. Then, once these truths are known, even more internal ones are taken in by those who have become enlightened. These even more internal truths together with the previous ones serve the Church as doctrinal teachings, the even more internal truths serving members of the internal Church, the other truths serving members of the external Church. Both groups of people, if they have led lives in accord with those truths, are raised to heaven among angels, and there they are endowed with angelic wisdom, which is the product of truths still more internal, and finally of inmost truths in the third heaven. These truths together with the previous ones in their own order terminate in the last and lowest, which belong to outward sensory perception, and exist together within them. From this it is evident that interior truths reside all together in the truths belonging to the literal sense of the Word, for the latter are the last and lowest, as has been stated. Within things that are last and lowest those which are more internal ones position themselves all in sequence, and within them they exist all together, see 9828, 9836. From this it is evident what should be understood by the whole of Divine Truth present on the level of sensory perception, meant by the requirement that all the blood was to be poured out at the base of the altar.