Nettie Colburn Maynard - Was Abraham Lincoln a Spiritualist? (1891)
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No, next question? There's been over a century of debate about Lincoln's religious views but spiritualism isn't part of that. Sure people have tried to rope him into that arena (this book is one example) but even the best attempts ("best" being quite relative here) rely on a lot of hearsay and assumptions. Maynard did conduct seances for Mrs. Lincoln but that's about as far as it goes, except for one possible attendance by Lincoln. Her account is probably as tedious as it sounds but hey there are "spirit poems" in the back!