A person can receive only what is given them from heaven. John 3:27
This is an astounding statement made by John the Baptist in the New Testament. Nevertheless, it is completely true.
When we are ill and a surgeon operates on our physical body and helps us heal, it is Divine Good flowing into the surgeon's heart, Divine Intelligence flowing into his mind and Divine Power flowing into his hands that inspired and enabled the surgeon to heal us. The surgeon was simply manifesting and doing God's work on earth. Should we thank the surgeon? Of course! But we should thank God first.
When we are thirsty and hungry and someone offers us a cup of pure water and a bowl of soup, it is God's mercy flowing into this person by correspondence and influx that manifested as this nourishing meal.
Human beings are only empty vessels that are able to receive Good, Truth and Power from Heaven by influx. Good (unselfish Love) flows into our heart to urge us to realize God's will or Divine Love, Intelligence flows into our mind from heaven to give us the means and ideas to realize these noble intentions and Divine Power flows into our physical body as energy to express Love as useful actions in the world. Hence, we should always remember that we are only God's instrument in the world.
The Celestial (emotional), Spiritual (mental), Natural (physical) levels of the universe are discrete and separate. But they are linked by correspondence and influx. Thus, all the effects that we perceive in the physical world are instigated from the Celestial realm of purposes and the Spiritual realm of causes by correspondence and influx. And any Good that comes to us, whether this good is physical, mental or emotional, can only be given to us from Heaven.
God only sends us what is Good because He is Love itself. The evil that comes to us originates from the discordant fields of hell. These fields were generated over the ages by selfish human beings who were in self-love, love of the world and love of abuses. When we FREELY choose to act from self-love and self-intelligence, our being aligns itself with these discordant fields and God's healing power, goodness and protection from Heaven cannot properly flow into our soul and physical body.
The Lord from His Divine Essence, which is goodness, love, and mercy, is unable to deal in the same way with every man, because evils and their falsities prevent, and not only quench His Divine influx but even reject it. Evils and their falsities are like black clouds which interpose between the sun and the eye, and take away the sunshine and the serenity of its light; although the unceasing endeavor of the sun to dissipate the opposing clouds continues, for it is operating behind them; and in the meantime transmits something of obscure light into the eye of man by various roundabout ways. It is the same in the spiritual world. The sun there is the Lord and the Divine love; and the light there is the Divine truth; black clouds there are falsities from evil; the eye there is the understanding. So far as any one in that world is in falsities from evil he is encompassed by such a cloud, which is black and dense according to the degree of his evil. From this comparison it can be seen that the Lord is unceasingly present with everyone, but that He is received variously. Emanuel Swedenborg [HH 549]
The truth of the matter is this: Beginning in the Lord and coming by way of the spiritual world into persons and things in the natural world there is both general influx and particular influx. General influx passes into whatever exists in a state of order, particular influx into whatever does not exist in a state of order. Animals of every kind live in the order of their own nature and therefore receive general influx. The fact that they live in the order of their own nature is clear from their knowing at birth all they need to know, so that they do not have to receive any training to acquire it. But human beings do not live in a state of order or in accordance with any laws of order. Therefore they have the particular influx into them; that is, they have with them angels and spirits through whom that influx comes. If human beings did not have the angels and spirits with them they would plunge into every kind of wickedness and hurl themselves instantly into the deepest hell. By means of those spirits and angels a person is kept under the Lord's guidance and control. If human beings lived in the state of order in which they were created they would love their neighbour as themselves; indeed they would love him more than themselves, as the angels do. But the human being loves only himself and the world, and hates his neighbour, except so far as he - his neighbour - indulges him, letting him take control and giving him the world. Since therefore the way people live is totally contrary to heavenly order the Lord rules them by means of separate spirits and angels for each one. Emanuel Swedenborg [AC 5860]
THERE IS A UNIVERSAL INFLUX FROM GOD INTO THE SOULS OF MEN THAT THERE IS A GOD, AND THAT HE IS ONE.
The existence of an influx from God into man is implied in the general acknowledgment that all good which is in him and which is done by him, if it really is good, is from God; and also that all charity and all faith are from God. For it is written:
"A man can receive nothing, except it be given him from heaven." John iii. 27;
and Jesus said:
"Without me ye can do nothing." John xv. 5,
that is, nothing of charity or of faith. This influx is into the souls of men because the soul is the inmost and highest part of man, and influx from God enters into it, passes thence into what is beneath, and vivifies all according to reception. The truths of which faith will ultimately be formed enter indeed through the hearing, and are in this way implanted in the mind beneath the soul. The immediate effect of these truths, however, is only to dispose a man to receive influx from God through the soul, and his reception of influx is according to his disposition. Thus what would have been merely natural faith becomes transformed into spiritual, that is, real faith.
 This Divine influx into the souls of men inspires the idea that God is one because all that is Divine, in general and in particular, is God; and since all that is Divine forms a consistent unity, it cannot but inspire in man the idea of one God. This idea is confirmed continually as man is raised by Divine influence into the light of heaven. For angels in that light cannot compel themselves to utter the word for "gods." Therefore also in speaking they end every sentence with a uniform accent, a result of the influx into their souls of the unity of God.
 Although there is this influx, yet many people think that the Divinity is separated into several Persons of the same Essence, because as this influx descends it enters into forms that do not correspond with it; and influx is varied according to the recipient form. This happens in all the subjects of the three kingdoms of nature. It is the same God who imparts life to man and to beast, but the recipient form renders the life in the one case bestial and in the other human. A similar result follows when a man induces on his mind the form of a beast. The influx from the sun into every plant is the same, but is varied according to the form of each. There is the same influx into the vine as into the thorn; but if a thorn is grafted on a vine, the influx is changed and flows through the graft according to the form of the thorn.
 The case is similar with the subjects of the mineral kingdom. The light that flows into the lime-stone and into the diamond is the same: in the one is translucent and opaque in the other. As to human minds, they vary according to their forms. There are those which are inwardly spiritual, fashioned by faith in God and life from Him. They become translucent and angelic through faith in one God. On the other hand those become dark and bestial who believe on several gods, a belief which is but little removed from faith in no God. Emanuel Swedenborg [TCR 8]