He who walks with the wise grows wise

मन्दोऽप्यमन्दतामेति
संसर्गेण विपश्चितः ।
पङ्कच्छिदः फलस्येव
निकषेणाविलं पयः ॥

- मालविकाग्निमित्रम्

Even a dull person becomes sharp by keeping company with the wise, just like the turbid water which becomes clear when treated with the dust-removing fruit.

He who walks with the wise grows wise.
A man is known by the company he keeps.