We shall be better able to understand that process by studying how the seeds of different trees select from the common environments different materials, and absorb and assimilate different quantities of elements. Suppose two seeds, one of an oak and the other of a chestnut, are planted in a pot. The power of growth in both the seeds is of the same nature. The environments, earth, water, heat and light are the same. But still there is some peculiarity in each of the seeds, which will absorb from the common environments different quantities of elements and other properties which are fit to help the growth of the peculiar nature and form of the fruit, flower, leaves of each tree. Suppose the chestnut is a horse-chestnut. If, under different conditions, the peculiar nature of the horse-chestnut changes into that of a sweet chestnut, then, along with the changes in the seed, the whole nature of the tree, leaves, fruits will also be changed. It will no more attract, absorb or assimilate those substances and qualities of the environments which it did when it was a horse-chestnut. Similarly, through the law of "natural selection" the newly moulded thought-body of the dying person will choose and attract such parts from the common environments as are helpful to its proper expression or manifestation. Parents are nothing but the principal parts of the environment of the re-incarnating individual. The newly moulded inner nature or subtle body of the individual will by the law of "natural selection" involuntarily choose, or be unconsciously drawn to, as it were, its suitable parents and will be born of them. As, for instance, if I have a strong desire to become an artist, and if after a life-long struggle I do not succeed in being the greatest, after the death of the body I will be born of such parents and with such environments as will help me to become the best artist.

The whole process is expressed in Eastern philosophy by the doctrine of the Reincarnation of the individual soul. Although this doctrine is commonly rejected in the West, it is unreservedly accepted by the vast majority of mankind of the present day, as it was in past centuries. The scientific explanation of this theory we find nowhere except in the writings of the Hindus; still we know that from very ancient times it was believed by the philosophers, sages and prophets of different countries. The ancient civilization of Egypt was built upon a crude form of the doctrine of Reincarnation. Herodotus says: "The Egyptians propounded the theory that the human soul is imperishable, and that where the body of any one dies it enters into some other creature that may be ready to receive it." Pythagoras and his disciples spread it through Greece and Italy. Pythagoras says: "All has soul; all is soul wandering in the organic world, and obeying eternal will or law."

In Dryden's Ovid we read:—

"Death has no power the immortal soul to slay,
That, when its present body turns to clay,
Seeks a fresh home, and with unlessened might
Inspires another frame with life and light."

It was the keynote of Plato's philosophy. Plato says: "Soul is older than body. Souls are continually born over again into this life." The idea of Reincarnation was spread widely in Greece and Italy by Pythagoras, Empedocles, Plato, Virgil and Ovid. It was known to the Neo-Platonists, Plotinus and Proclus. Plotinus says: "The soul leaving the body becomes that power which it has most developed. Let us fly then from here below and rise to the intellectual world, that we may not fall into a purely sensible life by allowing ourselves to follow sensible images...." It was the fundamental principle of the religion of the Persian Magi. Alexander the Great accepted this idea after coming in contact with the Hindu philosophers. Julius Caesar found that the Gauls had some belief regarding the pre-existence of the human soul. The Druids of old Gaul believed that the souls of men transmigrate into those bodies whose habits and characters they most resemble. Celts and Britons were impressed with this idea. It was a favorite theme of the Arab philosophers and many Mahomedan Sufis. The Jews adopted it after the Babylonian captivity. Philo of Alexandria, who was a contemporary of Christ, preached amongst the Hebrews the Platonic idea of the pre-existence and rebirth of human souls. Philo says: "The company of disembodied souls is distributed in various orders. The law of some of them is to enter mortal bodies, and after certain prescribed periods be again set free." John the Baptist was according to the Jews a second Elijah; Jesus was believed by many to be the re-appearance of some other prophet. (See Matt, xvi, 14, also xvii, 12.) Solomon says in his Book of Wisdom: "I was a child of good nature and a good soul came to me, or rather because I was good I came into an undefiled body."

The Talmud and Cabala teach the same thing. In the Talmud it is said that Abel's soul passed into the body of Seth, and then into that of Moses. Along with the spread of the Cabala this doctrine (which was known as Transmigration and Metempsychosis) "began to take root in Judaism and then it gained believers even among men who were little inclined towards Mysticism. Juda ben Asher (Asheri) for instance, discussing this doctrine in a letter to his father endeavored to place it upon a philosophical basis." (Jewish Encyclopedia, Vol. XII, p. 232.) We also read, "The Cabalists eagerly adopted the doctrine on account of the vast field it offered to mystic speculations. Moreover it was almost a necessary corollary of their psychological system. The absolute condition of the soul is, according to them, its return, after developing all those perfections, the germs of which are eternally implanted in it, to the Infinite Source from which it emanated. Another term of life must therefore be vouchsafed to those souls which have not fulfilled their destiny here below, and have not been sufficiently purified for the state of union with the Primordial Cause. Hence if the soul, on its first assumption of a human body and sojourn on earth, fails to acquire that experience for which it descended from heaven and becomes contaminated by that which is polluting, it must reinhabit a body till it is able to ascend in a purified state through repeated trials." This is the theory of the Zohar, which says: "All souls are subject to transmigration; and men do not know the ways of the Holy One, blessed be He! They do not know that they are brought before the tribunal both before they enter into this world and after they leave it; they are ignorant of the many transmigrations and secret probations which they have to undergo, and of the number of souls and spirits which enter into this world and which do not return to the palace of the Heavenly King. Men do not know how the souls revolve like a stone which is thrown from a sling. But the time is at hand when these mysteries will be disclosed." (Zohar, II, 99 b.)

Like many of the Church Fathers the Cabalists used as their main argument in favor of the doctrine of metempsychosis the justice of God. But for the belief in metempsychosis, they maintained, the question why God often permits the wicked to lead a happy life while many righteous are miserable would be unanswerable. Then too the infliction of pain upon children would be an act of cruelty unless it is imposed in punishment of sin committed by the soul in a previous state. Isaac Abravanel sees in the commandment of the Levirate a proof of the doctrine of metempsychosis for which he gives the following reasons: (1) God in His mercy willed that another trial should be given to the soul, which having yielded to the sanguine temperament of the body had committed a capital sin, such as murder, adultery, etc.; (2) it is only just that when a man dies young a chance should be given to his soul to execute in another body the good deeds which it had not time to perform in the first body; (3) the soul of the wicked sometimes passes into another body in order to receive its deserved punishment here below instead of in the other world where it would be much more severe. (Commentary on Deuteronomy, XXV, 5.)

Christianity is not exempt from this idea. Origen and other Church Fathers believed in it. Origen says: "For God, justly disposing of his creatures according to their desert, united the diversities of minds in one congruous world, that he might, as it were, adorn his mansion (in which ought to be not only vases of gold and silver, but of wood also and clay, and some to honor and some to dishonor) with these diverse vases, minds or souls. To these causes the world owes its diversity, while Divine Providence disposes each according to his tendency, mind and disposition." He also says: "I think this is a question how it happens that the human mind is influenced now by the good, now by the evil. The causes of this I suspect to be more ancient than this corporeal birth." The idea of Reincarnation spread so fast amongst the early Christians that Justinian was obliged to suppress it by passing a law in the Council of Constantinople in 538 A.D. The law was this: "Whoever shall support the mythical presentation of the pre-existence of the soul, and the consequently wonderful opinion of its return, let him be Anathema." The Gnostics and Manichaeans propagated the tenets of Reincarnation amongst the mediaeval sects such as the Bogomiles and Paulicians. Some of the followers of this so-called erroneous belief were cruelly persecuted in 385 A.D.

In the seventeenth century some of the Cambridge Platonists, as Dr. Henry More and others, accepted the idea of rebirth. Most of the German philosophers of the middle ages and of recent days have advocated and upheld this doctrine. Many quotations can be given from the writings of great thinkers, like Kant, Scotus, Schelling, Fichte, Leibnitz, Schopenhauer, Giardano Bruno, Goethe, Lessing, Herder and a host of others. The great skeptic Hume says in his posthumous essay on "The Immortality of the Soul," "The metempsychosis is therefore the only system of this kind that philosophy can hearken to." Scientists like Flammarion and Huxley have supported this doctrine of Reincarnation. Professor Huxley says: "None but hasty thinkers will reject it on the ground of inherent absurdity. Like the doctrine of evolution itself, that of transmigration has its roots in the world of reality." ("Evolution and Ethics," p. 61.)

Some of the theological leaders have preached it. The eminent German theologian Dr. Julius Müller supports this theory in his work on "The Christian Doctrine of Sin." Prominent theologians, such as Dr. Dorner, Ernesti, Rückert, Edward Beecher, Henry Ward Beecher, Phillips Brooks, preached many a time touching the question of the pre-existence and rebirth of the individual soul. Swedenborg and Emerson maintained it. Emerson says in his essay on Experience, "We wake and find ourselves on a stair. There are stairs below us which we seem to have ascended; there are stairs above us, many a one, which go upward and out of sight."