Irving Fisher's first interest rate theory states that interest rate is time preference, manifested in a degree of impatience. The influence of his theory is widespread. Among others, John M. Keynes took his time-preference for liquidity-preference, while Paul A. Samuelson applied his inter-temporal setting to develop a biological theory of interest rate. This book first proves that Fisher had forced an extra equation into his model and then manipulated the excessive model to obtain his desired result. This book then derives the same Fisher theory, without impatience.