The Heart Sūtra Step-by-Step and in-a-Flash

The Heart Sūtra is one of the most well-known and often recited sūtras but, at the same time, this sūtra has also a very mysterious koan-like character seemingly challenging many of the fundamental Buddhist teachings, like the five skandhas, the twelve āyatanas, the eighteen dhātus, the twelve links of dependent origination, the four noble truths, etc. Many commentaries were written on this sūtra.