The ghanta is a handbell held in the left hand throughout Vajrayana ritual while the vajra is held in the right, and its meaning is inseparable from that pairing.
Wisdom and method together
In the pairing the bell is wisdom and emptiness and the vajra is method and compassion, and holding the two together throughout the rite states that these are inseparable, that the realisation the tradition seeks requires both, joined as the two hands are joined in the ritual gestures. The bell is rung at points in the liturgy, its sound understood as the sound of emptiness and as an offering, and its form is dense with meaning, the face of a deity on the bowl, a ring of syllables, and a handle topped by a half-vajra so that bell and sceptre together read as one divided object.
A statement made in metal
Because the handle of the bell is itself a half-vajra, the pair is in a sense a single implement parted into two, which makes the physical objects a compact expression of the doctrine that wisdom and method are ultimately one. The ghanta is thus never merely an instrument for marking the liturgy but a bearer of teaching held in the hand of the practitioner throughout, and the constant presence of the two together is a continual reminder of the union the practice aims at. The same bell appears in Hindu worship as the ghanta rung before the image, though the elaborate symbolism of the pair is particular to the Vajrayana.