This paper aims to investigate the origin and grammaticalization path of a modern Chinese word 至于(transcribed as 至於 in traditional characters), which originated from 至(verb of movement)+于/於(a function word indicating allative) in Archaic Chinese. In modern Chinese, 至于 has two major usages: (1) It is used in the form “不至于+VP” delivering the meaning that the situation would not reach such an extreme degree or adverse result; (2) It is used in the form “至于+Topic, Comment” introducing a new topic which is related to the topic that is previously mentioned. (Li[2006] called 至于 of this usage a “topic-shifter.”)By analyzing several pre-Qin texts, both excavated and transmitted, which presumably reflect languages of different times, this paper illustrates that the proto-type of “不至于+VP” in modern Chinese appears as early as in the Warring States philosophical texts. It is noteworthy that, in these texts, only 至於, no 至于, was followed by an object which indicates a degree, result, or situation, all of which can be described as a [-concrete] object. Also, the semantic scope of 至於 in Warring States period texts was by far broader than 不至于 in modern Chinese in that not only a verb phrase, but also a near demonstrative 此，a noun (including both a concrete and an abstract noun) or a noun phrase, verb phrase, and even a sentence can be used as the object of 至於. Semantically speaking, the object of 至於 in Warring States period texts could be either adverse or favorable, while the object of 不至于 in modern Chinese is almost always adverse. This shows that the semantic scope of 不至于 in modern Chinese shrank drastically compared to that of 至於 in Warring States period philosophical texts. Meanwhile, it is noteworthy that both 至于 and 至於 were already used as a topic shifter in the Warring states period texts through the change of constituency and reanalysis of 至(verb of movement)+于/於(a function word indicating allative) into 至于/至於(a preposition).