In my physics textbook chapter of work 3 statements are made which I am having trouble sorting through. 1. When W>0 the system's energy increases, when W<0 the system's energy decreases. 2. ΔE = ΔK+ΔU+ΔTherm = W 3. ΔU = -W Here is where my confusion begins. If I move a 1kg brick from 0m to 1m I have added potential energy, more energy is stored in the system. Statement 2 asserts that because ΔU increases, ΔE will also increase and work will be positive. Statement 1 says that W>0 so the system's energy increases. But statement 3 says that ΔU= -W, but we can see clearly that ΔU was positive and that work is also positive. I am missing something. Please help.