Vaisesika Sūtra 5.1.15

मणिगमनं सूच्यभिसर्पणमदृष्टकारणम् ॥१५॥

maṇigamanaṁ sūcyabhisarpaṇam adṛṣṭakāraṇam ॥15॥

[मणि-गमनम् (maṇi-gamanam) - attention to gem; सूचि-अभिसर्पणम् (sūci-abhisarpaṇam) - pointed attention to needle; अदृष्ट-कारणम् (adṛṣṭa-kāraṇam) - has unseen cause;]

The attention to a gem or pointed attention to a needle has an unseen-cause.