《老子》「三十輻共一轂當其無有車之用」一語，歷來對此產生「車之用」的「無」，有轂中空虛處、車中空虛處、轂與車中空虛處、未明確指出之四種詮釋；對「三十輻」這個數目，也有月數和五藏六氣兩種說法。而諸家詮釋所持之理據又有（1）句型（2）〈考工記〉二個源由。本文分析諸學者提出的兩種句型結構，發現所傳達的訊息並無差別，皆以「有」說明「無」之為貴；真正的關鍵仍在車的功用究竟是什麼、是由哪個部位的「無」來實現的；而歷來學者以文獻證文獻的方法闡述先秦車制時，充滿「以〈考工記〉證《老子》語、以《老子》語證〈考工記〉」的矛盾現象。本文乃根據考古專家學者們對先秦車輛實物的研究成果，探討先秦車輻之數及其緣由、「轂中空虛處」是否確實是上古行車的必要條件等問題；因而得知先秦之車皆以輿與輪為主要組成部分，而輻條數目之多寡，多基於實用的考慮。本文因此推論出老子以「三十輻共一轂」代表車輛之「有」的原因為：車輛之主要結構、琢削頗費工、引人矚目。

What is the ＂invisible part＂ which produces the ＂function of a wheeled vehicle＂ mentioned in Laozi's words ＂30 spokes come together at the hub of a wheel; the function of the vehicle is in the invisible part ＂ which, so far, is interpreted as four different readings: the space in the hub of the wheel, the space of the seat, both the space in the hub and the seat, or not specified. As to the number of the spokes, there are two interpretations: based on the number of days in a month; based on the concept of six types of energy generated by five major organs of human body. The sources of these interpretations are (1) sentence structure (2) the ancient document ＂Kao-gong-ji＂. This article analyzes the two sentence structures suggested by many scholars and discovered that there is no real difference between the two in terms of the conveyed meaning. Both structures use ＂the visible part＂ to indicate the value of ＂the invisible part＂. The function of a wheeled vehicle and its realization by which ＂invisible part＂ is still the question to be answered. As to the document review method applied by scholars in examining the structure of Chinese ancient wheeled vehicles, ＂Kao-gong-ji＂ is used to account for ＂Lao-zi' and, vis-à-vis, ＂Lao-zi＂ for ＂Kao-gong-ji＂. This article thus, based on the results of archaeological researches, looks into the number of spokes on pre-Qin vehicles and the reason for it; also whether the ＂space in the hub＂ is essential for vehicles to be able to function. Additionally this article confirmed that the seats and wheels were the two major components of Chinese ancient form of transports. The variation of or number of spokes was based on practical considerations. This article therefore learnt that, the reasons for Lao-zi to use ＂30 spokes come together at the wheel hub＂ to convey the concept of ＂have＂ are as follows: they are major parts of a vehicle; the amount of work to produce them; and the level of attention from viewers.