# Maximal Margin Classifier (Optimal Separating Hyperplane) Overfitting when dimension is too large?

In "Introduction to Statistical Learning", for maximal margin classifiers, they say:

"Although the maximal margin classifier is often successful, it can also lead to overfitting when $$p$$ (the number of dimensions) is large," (p. 341)

also in "Elements of Statistical Learning":

"Again one can enlarge the space using basis transformations, but this can lead to artificial separation through over-fitting" (p. 135)

I don't seem to understand this. Could someone please explain why a large dimension can cause the separating hyperplane to overfit? How does increasing the dimension makes separation possible? (even if it's just artificial)?