A far cry from the “Shadow” of serial radio drama fame is the Greek notion of the shadow (skia) that shows up in Colossians 2:17. 2:6-15 is a difficult passage, but whatever the shadow is, it is not the reality that is in Christ. Here are verses 16 and 17, first in the NetBible version, then in Greek:
2:16 Therefore do not let anyone judge you with respect to food or drink, or in the matter of a feast, new moon, or Sabbath days – 2:17 these are only the shadow of the things to come, but the reality is Christ!
2:16 μη ουν τις υμας κρινετω εν βρωσει και εν ποσει η εν μερει εορτης η νεομηνιας η σαββατων 2:17 α εστιν σκια των μελλοντων το δε σωμα του χριστου
The skia appears to be contrasted with the term soma, which is normally translated “body”; here, soma may indicate an expanded or more thorough notion such as “reality” or “substance”–that which is observable. There remains a possibility that “body” here refers to either a literal or figurative “Body of Christ,” i.e., either the physical flesh of Jesus, or the 2nd incarnation, the church. So far, I have found that scholarly opinion leans toward a more expanded meaning of soma. Whatever it implies, it is certainly the positive element in the expression, contrasted with a more limited shadow.
The skia (=the shadow, of rules and regulations) does not “know.” Some of those rules may indeed be well-conceived and well-intended, but the substance of them is apprehended, experienced, known, seen in Christ.