Mapping linguistic forms, such as the word ‘cat,’ to their corresponding meanings, such as the concept of a ‘cat,’ is a fundamental property of language. In an ideal scenario, this mapping occurs on a one-to-one basis, where each form uniquely corresponds to a specific meaning, and vice versa. However, there are instances where this neat one-to-one relationship breaks down, and a single form takes on multiple meanings. This intriguing phenomenon is the primary focus of the FOME-project. The central objective of the FOME-project is to delve into how native speakers articulate their thoughts, desires, regrets, and other cognitive nuances through clausal complementation. Specifically, the project aims to explore the intricate ways in which individuals indicate the extent to which their statements contain familiar or new information, established facts, or conjectures. This exploration will be grounded in two key approaches: (a) insights derived from studying microvariation in Modern Greek dialects and macrovariation across diverse languages, and (b) utilization of an array of methodological tools encompassing fieldwork, experimental research involving questionnaires, statistical analyses, and self-paced reading tasks, examination of diachronic syntax, and engagement with theoretical linguistics. Through this comprehensive investigation, the FOME-project seeks to illuminate critical questions. These questions encompass the intercomparability of different languages, the boundaries of human perception and cognition that can be encoded within grammatical structures, and the intricate pathways through which these aspects gradually evolve into grammatical forms.