My experience of men has neither disposed me to think worse of them, or indisposed me to serve them; nor in spite of failures, which I lament, of errors which I now see and acknowledge; or of the present aspect of affairs; do I despair of the future.
The truth is this: The march of Providence is so slow, and our desires so impatient; the work of progress is so immense and our means of aiding it so feeble; the life of humanity is so long, that of the individual so brief, that we often see only the ebb of the advancing wave and are thus discouraged. It is history that teaches us to hope.

Letter to Lieutenant Colonel Charles Marshall (September 1870)