From Larry Cunningham's latest book, Berkshire Beyond Buffett, which is released tomorrow. The book has a bunch of great info on Berkshire subsidiaries and the people involved in them.
Reinvest profits in promising businesses; this is the central bastion of Berkshire culture driving its acquisitions. Do this to stimulate a complacent workface as James Hambrick did at Lubrizol; to build a company through steady bolting-on and tucking-in the way MiTek does; or to become an industry force like Berkshire Hathaway Energy. But avoid adding capital to businesses that do not generate high returns...