And the Constitution also says:
"The Senate shall have the sole Power to try all Impeachments."
Are you aware of other trials in our system that can't call witnesses?
I didn't say that the Senate could not call witnesses. I said that the Senate cannot be part of a process that introduces NEW evidence/witnesses to an Article of impeachment being considered by the Senate. The Constitution gives this authority solely to the House of Representatives. They develop the evidence and put it before the Senate in the form of an Article of Impeachment. Period. The Senate is LIMITED to consideration of only that which comprises that article, not anything extraneous to it, which certainly any "new" testimony or evidence would be. The Senate is not allowed to help the House develop it's case and the House is not permitted to tell the Senate how to judge it's case. Allowing new testimony/witnesses would make both the House and the Senate co-developers of the evidence which the Constitution strictly prohibits.