In his paper "On Denoting" and his later book "Problems of Philosophy", Bertrand Russell brought a great deal of attention to the distinction between "knowledge by description" and "knowledge by acquaintance". Gilbert Ryle is similarly credited with bringing more attention to the distinction between knowing how and knowing that in "The Concept of Mind". In "Personal Knowledge", Michael Polanyi argues for the epistemological relevance of knowledge how and knowledge that; using the example of the act of balance involved in riding a bicycle, he suggests that the theoretical knowledge of the physics involved in maintaining a state of balance cannot substitute for the practical knowledge of how to ride, and that it is important to understand how both are established and grounded. This position is essentially Ryle's, who argued that a failure to acknowledge the distinction between "knowledge that" and "knowledge how" leads to infinite regress.