In short, after a certain time of proper meditation on oneself, one will start to see an inner white light in one's head. By concentration one can sustain this white light and make it more bright and continuous. The light is actually the awareness of one's own divine self. Eventually it will fill the entire body and be permanent. This is the true enlightenment, or self-realization. Hermetic alchemy is basically this process of self-realization. When the first light appears it resembles the white light of the moon. That is why the Moon is the symbol for Albedo, Whiteness, the second phase of the Great Work. When the light becomes permanent, the symbol becomes the Sun, and this third stage is called Rubedo, Redness.

In alchemical iconography, we see some fine examples of this self-realization through the symbol of the Sun (the inner light) shining in and through the alchemist.

His Secret Booke of the Blessed Stone called the Philosopher's, by Artephius, 1624

This book is a text supposedly written by the 14^th century Nicolas Flamel (Book of Hieroglyphical Figures), with added commentary, translated from Latin into English. The illustration shows the sun above an opened tomb, the classical symbol for the resurrection of the soul. Sometimes it is a man or more often a king rising from the tomb, but the sun is more significant because it is shows that the inner light has broken through, and is permanent.

Rosarium Philosophorum, anonymous, 18th century copy

from the library of John Ferguson, Glasgow, England

The Rosarium philosophorum,(Rosary of the philosophers) is recognized as one of the most important texts of European alchemy. Originally published in the 1550, it is extensively quoted in later alchemical writings.

Here we see again the Sun rising from the tomb, and in the image to the right is the risen alchemist, here identified with Christ (who is the Inner Sun), with the Sun rays behind his head.

Clavis Artis, attributed to Zoroaster, 1738

from Biblioteca dell'Accademia Nazionale dei Lincei, Rome, Italy

The author, who attributes his work of Clavis Artis (The Key to the Art) to a character from antiquity (Zoroaster), could be Abraham Eleazar. It is also assumed that this work would have a connection with a Rosicrucian order, "Der Orden der Gold- und Rosenkreuzer".

Abraham Eleazar also wrote Uraltes Chymisches Werk (Ancient Chemical Work), but his name is most likely a pseudonym for the publisher, Julius Gervasius of Schwarzburg.

Clavis Artis features numerous watercolor illustrations depicting alchemical images, as well as pen drawings of laboratory instruments.

It is not only a nice watercolor painting, but it depicts the reborn alchemist with the Sun as head, indicating the inner light that appears inside one's head. He holds the three flowers of Body, Soul and Spirit in one hand to show that all three have been unified.

Below is the same illustration from another version of the book: 

Clavis Artis, 1738, from Biblioteca Civica Attilio Hortis in Trieste, Italy

Ritter-Krieg, Johann Sternhals, 1680 

Ritter-Krieg, or The War of the Knights is an alchemical text, published in Hamburg in 1680. War of the Knights is a medieval alchemical narrative, written in the form of judicial combat between the allegorical figures of the Sun (gold) and Mars (iron).

Scrutinium cinnabarinum seu Trigacinabriorum, by Gottfried Schulz, 1680

This work is on cinnabar (a mercuric sulfide or native vermilion), the common ore of mercury. The author describes where it is found, how it is refined, pharmaceutical preparations, etc.

The awareness of the alchemist is now fully in his light body, shining like a sun, with his bodily personality behind him as a pale shadowy reflection of his true self.

from an unknown manuscript