But the soul is the only part that truly feels fear or grief. The soul is the only part that can choose to accept these feelings or reject them based on its thoughts and beliefs. You can make sure your soul suffers nothing. Don't let it form harmful opinions. The mind is complete by itself. It needs nothing else, if it doesn't create its own needs. Since it needs nothing, nothing can trouble or block it — unless it troubles and blocks itself.
But as for the soul, which indeed, can only be truly sensible of either fear or grief; to which only it belongs according to its different imaginations and opinions, to admit of either of these, or of their contraries; thou mayst look to that thyself, that it suffer nothing. Induce her not to any such opinion or persuasion. The understanding is of itself sufficient unto itself, and needs not (if itself doth not bring itself to need) any other thing besides itself, and by consequent as it needs nothing, so neither can it be troubled or hindered by anything, if itself doth not trouble and hinder itself.