अल्पाक्षरमसन्दिग्धं सारवत्विश्वतोमुखम् ।
अस्तोभमनवद्यं च सूत्रं सूत्रविदो विदुः ॥
alpākṣaram asandigdhaṁ sāra-vat viśvato-mukham |
astobham anavadyaṁ ca sūtraṁ sūtra-vido viduḥ ||
(Vāyu Purāṇa; Skanda Purāṇa; Viṣṇu-dharmottara)
“Knowers of sūtras know a sūtra (aphorism) to be concise [i.e., of a minimum of letters], unambiguous, substantial [i.e., expressive of the essence of its subject-matter], comprehensive, without any pause [i.e., stoppages or insertions], and irreproachable [i.e., faultless].”