Do people have intrinsic value?

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Do people have intrinsic value? For several years now I've worked with people with disabilities of all sorts and degrees of severity. It has made me question a lot of things and think about why people matter. There are so many external elements, positive and negative, of these peoples lives I've given consideration: the things that impact our community and others in it but is there something else underneath all these things that gives value to people? I believe they do although I cannot express why. Just by asking these questions I feel uneasy like I'm being disrespectful by discussing peoples existence like a math equation. So my question regards that weightiness I experience and where it comes from. (Could you recommend further reading?)