What does this sentence exactly mean?

Question

There is a really long sentence I came across and I can't seem to decipher the entirety of the sentence. Especially the bolded part. I can't seem to really get what it means by "relating illness."

Because Western medicine takes more of a materialist approach, relating illness only to causes of disease and biological actions that can be measured or seen, the spiritual foundation of TCM makes skeptics doubt the validity of many traditional Chinese treatments, especially when these treatments include the use of substances like mercury or animal bones.

Thanks in advance!

Answer 1

You have to consider "relating (something) to (something else)".

In your example these are (illness) and (causes). See relate:

2. verb
   The way that two things relate, or the way that one thing relates to another, is the sort of connection that exists between them.