Assalamu alaykum Moulana
Is the Qalb (Heart), Aql (Mind) and Nafs (Ego) part of the Ruh (Soul), or is the Ruh a separate entity? Please elaborate on how they are all connected.
وَ عَلَيْكُمُ السَّلاَمُ وَ رَحْمَة ُالَّلهِ وَ بَرَكاتُهُ
These are all separate entities.
The Qalb - the spiritual heart - is the control centre and supply centre for the body. It plays the same role spiritually which the physical heart plays physically. Depending on the condition of the heart, it can either supply the body with positive energy (Noor) which will result in the person doing good actions with his body, or it can supply it with negative energy (darkness), which will result in the person doing evil actions with his body. The heart is acted upon by the Nafs and the Rooh.
The Nafs - carnal desires - refers to a collection of desires which every person has inside himself. These desires in their original form are evil, and pull the person towards sin. Thus the Nafs, in its original untamed and wild form, acts upon the Qalb by polluting it with darkness, the negative energy which the heart then supplies to the rest of the body, resulting in evil actions.
The Rooh - the soul, which represents the very existence of a person - is made of Noor. It is responsible for illuminating the heart with Noor, so that the heart can pump it into the rest of the body. However, due to the original state of the Nafs being as I described above, it overpowers and weakens the Rooh, and does not allow it to pump Noor into the heart.
The Aql - a person's intellect and intelligence - in its sound form, plays the role of guiding a person towards understanding the need to strengthen the Rooh and weaken the Nafs, so that the heart can pump positive energy instead of negative.
Thus the entire effort of Tazkiya - spiritual purification - is based on subduing and taming the Nafs, an effort which will automatically strengthen the Rooh at the same time, so that the heart can be purified, and the darkness that was there due to years of domination by the Nafs, can be replaced by Noor from a now strong Rooh. This is what we have been tasked with in this worldly life, and our success or failure in Aakhirat is based on this.