They have denied death, either by integrating it with life or by promising to man immortality. Or, again they have denied life, considering it as a veil of illusion beneath which is hidden the truth of Nirvana.
So philosophers, or religious men, deny or mask this collective quality shared among men by either: focusing on only the life part by using it as a way to earn immortality by how one lives OR they deny the death mpart by geaching of continued life and reaching nirvana