Fed receives phenominal gains from T-bills

We have to appreciate how the Fed receives phenomenal gain from T-securities---and the cost to society.
Let us review how the Fed and Congress create fiat money. Congress grants a T-security to the Fed (asset) and the Fed credits the Treasury’s account (Federal Reserve Notes) as a liability. The checks written by the Treasury on that credit will then be honored by the check clearing procedure of the Fed.
[Granted, this is a vast simplification of the process. The basic accounting by the Fed can be reviewed at 2009 Annual Report to Congress by the Board of Governors from page 448 ,
http://www.federalreserve.gov/boarddocs/rptcongress/annual09/pdf/ar09.pdf and Treasury accounting breakdown is accessible at http://www.fms.treas.gov/mts/mts0610.pdf.]

Congress gets to spend the fiat money so created and the Fed holds the security and receives interest. When the security matures, the Treasury must redeem the security. The value of fiat money initially created must then be paid to the Fed and becomes gain.
The Fed has an accelerating option--it can sell the security. Arrangements are made whereby the Treasury acts as auctioneer and Primary Dealers are required to submit bids. Bids may be submitted to the New York Fed or to the Treasury. Upon maturity of the security, the Treasury redeems the security from the holder. The Fed receives the (bid) value of the security upon the sale.
By either of the two methods, the Fed has received the value of the security. The total value of all issued T-securities becomes a gain for the Fed.
The method used by Congress to redeem the security, and the interest incurred, is beyond the scope of this writing. THINK---more T-securities.