"Sorrows are the best educator." This quotation is by -

• Alfred Tennyson is a famous Victorian poet.
• His famous quotations:
- A man can see farther through tear than a telescope.
- Knowledge comes but wisdom lingers.
- Sorrows are the best educator.
- The old order changeth yielding place to new.
- Authority forgets a dying king.
- Who are wise in love, love most, say least.
- I will never rest from travels, I will drink life to the lees.

Source: The Oxford Dictionary of Quotation.