√SAN root. “think, use mind; (trans.) ponder, consider in thought”
Tolkien used this root and ones like it on-and-off for Elvish “thought” words throughout his life. The first manifestation of this root was in words from the Gnomish Lexicon of the 1910s like G. sana- “can, know how to, have knowledge, craft or skill” and G. santhi “knowledge, experience (in) or skill (in)” (GL/67), which suggests a (hypothetical) early root *ᴱ√SANA “know”, though such a root does not appear in the contemporaneous Qenya Lexicon. In etymological notes associated with the Ósanwe-kenta essay from 1959-60 Tolkien gave:
√SAM mind, think, reflect, be aware. sāma a mind. sanwe an act of thinking, a thought (*sam-we). ósanwe interchange of thought (between 2 samat). sanwekenda thought-inspection, thought-reading. sanwe-menta thought-sending, mental message (VT41/5).
However, in notes associated with óre that were contemporaneous with The Shibboleth of Feanor from 1968, Tolkien gave Q. sanar = “mind, reflector, thinker” (VT41/13), and in Late Notes on Verbs from 1969 (LVS) Tolkien gave the root √SAN “think, use mind; ponder, consider (in thought)” with derivative Q. sanwë “(act or process of) thinking, thought” (PE22/158). Thus 1959-60 √SAM “think” >> 1968-69 √SAN “think”, perhaps a restoration of the Gnomish root from the 1910s.
References ✧ PE22/158; VT41/16
√SAM² root. “mind, think, reflect, be aware”
References ✧ PE17/183; VT41/5
?ᴱ√SANA root. “*know”