"The paths of glory lead but to grave." - This quotation is by -

• Thomas Gray is known as a Graveyard poet.
• His famous quotations:
- 'Full many a flower is born to blush unseen,
   And waste its sweetness on the desert air',
       (An Elegy Written in a Country Churchyard)
- 'Where ignorance is bliss, it is folly to be wise',
- 'The paths of glory lead but to grave'.

Source: Encyclopedia of Britannica and The Oxford Dictionary of Quotation.