The central teaching is the doctrine of emptiness (śūnyatā): all phenomena are empty of any inherent, independent existence. This is encapsulated in the famous statement “form is emptiness, emptiness is form,” which points to the insight that what is usually taken as solid and self-existing is, upon deeper examination, devoid of fixed essence. The five aggregates—form, feeling, perception, mental formations, and consciousness—are highlighted as examples of this, showing that even what is taken to be “self” is a contingent process rather than a permanent entity. Emptiness here does not signify a nihilistic void, but the fact that things arise only in dependence upon causes, conditions, and conceptual designation.

Because all things lack inherent nature and arise dependently, the sutra indicates that ultimate reality cannot be captured by dualistic concepts such as existence and non-existence, gain and loss, or purity and impurity. By realizing this emptiness, the practitioner is said to transcend the habitual split between subject and object, self and other, and even the apparent divide between samsara and nirvana. This wisdom is described as the perfection of wisdom (prajñāpāramitā), the liberating insight that dissolves the mistaken belief in solid, independent existence. In this way, the teaching presents emptiness as the key to freedom from fear, delusion, and suffering, and as the heart of the path to enlightenment.