In quasi-static processes, the relationship dQ = dE + dW holds, but when dW = -dE, it raises the question of whether dQ can equal zero, suggesting no heat exchange. This confusion is particularly relevant in isothermal quasi-static processes, where dQ is not zero. The reference to Reif's Fundamentals of Statistical and Thermal Physics indicates that the work done by the system is defined as dWr = -dEr, implying that dW = -dE is specific to certain conditions. However, it is argued that a system cannot remain in a particular thermodynamic state if its internal energy changes, indicating that the equation may only apply to adiabatic changes. Understanding these distinctions is crucial for accurately interpreting thermodynamic processes.