So what did we learn from Bill Priestap’s compendious and revealing testimony?

• We learned that the FBI and Justice targeted and took action against Trump.
• We learned that the FBI, according to Priestap, is incapable of securing a FISA warrant with information that isn’t credible, although the judge’s approval of the warrant means by definition that the information is credible.
• We learned that the FBI believes political interference in an investigation can be proper as long as the bureau isn’t acting purely politically.
• We learned that the FBI did send at least one asset to do to the Trump campaign an activity that even the bureau would call “spying” — if it were done by foreign operatives.
• We learned that the origins of the Trump-Russia tale will never be fully understood until the part played by British intelligence is made clear.

That’s an awful lot to take away from one largely neglected transcript. But it suggests just how much remains unknown about the Trump-Russia investigation while providing a glimpse at the people that want to keep it that way.