Existing research has shown that there is much variation in diachronic development and borrowability rates across different semantic fields in English, but most work up to now has focused on specialized or technical vocabulary, rather than fields associated with how people express and conceptualize their feelings and thoughts. While some studies have explored the historical evolution of the emotion lexicon (e.g., Diller [2014]) and, to a lesser extent, the cognition lexicon (e.g., Kiricsi [2010]), the contrastive study of these semantic categories has yet to be a focus in the research landscape. Therefore, this paper aims to explore the development of the cognition and emotion lexicon over a period of thousand years, from Old to Present-Day English. We compare the emergence of words in these two semantic fields across three key dimensions: semantic subfields, source languages of roots and morphological structure. For this purpose, we created a sample of approx. 1400 nouns on the basis of the Historical Thesaurus of English (HTE; categories: 02.01 mental capacity and 02.04 emotion) and analysed their etymology with the help of the Oxford English Dictionary. To annotate the lexical items in our sample, we used the methods of formal-morphological analysis (e.g., Tyschenko [2003]; Krykoniuk [2022]) and semantic analysis (e.g., Pons-Sanz [2022]; HTE [2023]). We analyse our sample with clustering techniques (i.e., Principal Component Analysis and Correspondence Analysis) to determine general trends across the two lexicons (e.g. a greater involvement of Latin roots and compounding in the formation of the cognition lexicon, and Norse-derived roots and conversion in coinage of nouns referring to emotion), as well as specific features of each period of the English language (e.g. the significant impact that the Middle English period had on the lexicalization of memory, fear, compassion, pleasure and suffering, and the early integration of French-derived terms, as suggested by word-formation processes).