I love people who provide free scientific material for college student (or overall everybody). I am in religious country and I am ex-Muslim . In my perspective , if I were to choose prophet for humanity , I would choose people who educate people (or provide education material -books , papers, etc- for people) freely .<p>p.s. no offence . I am not saying people who selling their books are bad guys, not at all . I am just saying people who provide free material in my opinion are doing something incredible to humanity .<p><i>update</i> : When I am saying &quot;educate people* , I absolutely mean science.