According to Avicennayan and Sadrayan's readings, despite all their differences, the "substance" is a quiddity that either exists outside without the subject, or if it exists in the subject, the subject also needs it for its existence. In contrast to " accident", it is a quiddity that is always found in a subject that does not need it. This division is based on the existence or non-existence of quiddities.

Sheikh Ishraq's starting point for the discussion of truth is "I" and the awareness of "I", not existence. In this view, "I" is a self-emerging truth that has knowledge of itself, and knowledge of others is created by paying attention to others. Therefore, what attracts the attention of "I" in the first step of the emergence of objects is the conscience and self-discovery of objects.

Then, in the second step, through the lens of intuition, the way things arise is brought to the attention of "I" in such a way that if the luminous facts, which are full of presence and light and perceive themselves, are found to be true to themselves and become conscience. They are "luminous substance" and if they are found to be existentially dependent on the other and conscience, they are "luminous accident".

Also, on the other hand, if the facts that are found absent from themselves, are found and realized independently of others, they are called " dark substance " and if they are found and realized independent of others, they are called "dark accident".