This Book provides theoretical framework for Language Maintenance Studies based on Ludwig Wittgenstein's famous conceptual work, Philosophical Investigations. This book suggests that the later Wittgenstein can serve as fundamental tool to help Indonesian linguists to deepen their exploration in term of developing linguistics theory. Since we have all known that theory is only called theory when a theory never satisfies the scientists scientific enterprise. It is translated from Bahasa Indonesia to English by (the late) M. Helmi Fuad.