Two letters on causation and freedom in willing, addressed to John Stuart Mill with an appendix on the existence of matter, and our notions of infinite space (Lee and Shepard, 1869)
"This book presents two letters by the author to John Stuart Mill. In these letters, Hazard discusses causation and freedom in willing. He also discusses the existence of matter, notions of infinite space, and other various philosophical topics" (PsycINFO Database Record (c) 2008 APA, all rights reserved)