"What should we think of a farmer who allowed his finest fields to lie fallow year after year? Yet men neglect their souls; and besides being unprofitable, these inward fields become full of weeks, and exceedingly foul. You see to everything else, will you not see to your souls?" (From Spurgeon's Sermon Notes)
Recommended reading:
The Forgotten Spurgeon, by Iain Murray
A Defense of Calvinism - by Charles Spurgeon