Originally, one soul of Adam was created, which divided into 600,000 souls, each of which divides into a great number of sparks.
However, the spiritual doesn’t divide into parts. Therefore, in reality there exists only one soul of Adam and it is contained wholly within each individual. The soul is divided into 600,000 parts by man’s egoism.
Initially, egoism expels and distances the Light from the soul. But if the ego undergoes correction through the study of Kabbalah, then the common soul shines in it.
Therefore, there are various circumstances with regard to the person:
1. He feels his individual soul and doesn’t understand that it is – the common soul,
2. Corresponding to the level of unity with the souls, the Light of the common soul shines within him,
3. When egoism is completely corrected, he feels that his soul exists in everyone, and the common soul shines for him to the fullest degree, as it does in Adam.
From here the three periods of man’s spiritual growth are created:
1. A spark of the soul,
2. The individual soul – perceives itself to be a part of the common soul, which brings about a feeling of lovesickness,
3. Approaches perfection in bestowing to the Creator; connects to the common soul.
Therefore, if there remains to be even a single uncorrected soul, there remains a lack of Light in all the souls. Also, by correcting itself, each soul evokes the Light of the common soul, thus evoking the correction of the entire generation. This is how the souls are dependent upon one another.
After its correction, each soul applies efforts to raise its entire generation to the spiritual level it has attained.
Because the particular and the general are equal, everything the souls went through in all the generations, each individual soul also goes through when it connects with them – all the flaws of all the generations, and all their corrections.
This is why one who possesses even the smallest soul, by aspiring toward bestowal and love, acquires the common soul.
Even if just one person from the generation attained the common soul, he has the ability to bring his entire generation to his state. (From the article “600,000 Souls” by Baal HaSulam.)