天 Tian, highest principle from Chinese ancient texts
Below are excerpts from selected chief ancient Chinese texts of books that mention the highest concept of 天 Tian
(For ease of reference, Mandarin普通話 spelling is used throughout instead of Cantonese粤語. Mandarin has only come into being after Mongolian control around AD1290 , whereas Cantonese has been in existence since BC200. Mandarin has obvious weaker matching rhythm of pronunciation to all pre Qin 先秦 writings, whereby Cantonese does better in comparison. )
Book 易經 Yijing (六十四卦)
天行健 君子以自強不息
Book 書Book(尚書)
惟上帝不常 作善 降百祥,作不善 降百殃
天作孽 猶可逭 ; 自作孽 不可活
皇天無親 惟德是輔
紂有臣民億萬而億萬心，周有臣三千惟一心
Book 詩經Poetry
昊天 上帝 上天 皇天 ,天作,天命,天降,天賜
Book 禮記Law(包含"樂記")
天不遺耆老,天殃,祭天
禮必本於天
天道至教
天子祭天地,祭四方,祭山川,祭五祀
Book 樂經Musics(亡佚lost)
Book 老子Laozi
天道無親，常與善人。
天之道,猶張弓,高者抑之,下者舉之。
天之道，損有餘而補不足。
早服曰重積德,重積德則無不克
功成身退天之道。
無為而無不為（表面沒做，但卻事實上甚麽都做成了） 大小多少（要去壯大弱小的，要增多那些缺少的）
Book 孔子（論語Confucius Analects）
君子憂道不憂貧。天何言哉？天將以夫子為木鐸。
天生德於予。唯天為大。 志於道，依於仁，據於德。畏天命。
不患寡而患不均
子曰 苛政猛於虎（苛刻的政務）
子曰 志士仁人，無求生以害人，有殺身以成仁。
Book 墨子Mozi
天之志者，義之經也。
天欲人之相愛相利，不欲人之相惡相賊。
天下百姓，上同天子而不上同於天。
法儀，尚同（一樣的價值觀念和道德精神），
兼愛，節用，尚賢，非命，天志，非攻，非儒
一人一義，十人十義。
順天意者，義政也。反天意者，力政也。（力政就是暴政）
得罪於天，無所逃避
Book 莊子Zhuangzi
（辯證邏輯）
齊物論，不真不誠，不能動人，
陰中有陽，陽中有陰（屬於道家老子的支持者）
Book 公孫龍子 Gongsun Long（秉）
（辯證邏輯）
白馬非馬，堅白論
Book 楊朱 Yangzhu
（辯證邏輯）
古之人，損一毫利天下，不與也，
悉天下奉一身，不取也。
人人不損一毫，人人不利天下，天下治矣。
Book 中庸Zhongyong
（誠，真）
中庸，不偏不倚。
誠者，天之道也；誠之者，人之道也。
誠者，不勉而中，不思而得，從容中道，聖人也。
誠之者，擇善而固執之者也。
誠則明也，明則誠也。
至誠無息，不息則久。
Book 大學Daxue
在明明德，在止於至善
格物 至知 誠意 正心 修身 齊家 平天下
誠其意者，毋自欺也。
先秦華夏與後秦很大差異。今日的華人已經不再具備華夏的品格。秦毀華夏大於建設。
The Chinese have become totally different from what those in the preQin era had been. PreQin Chinese were more like what preQin texts had described and shown, bold, fearless, genuine, straightforward, frank, courageous, shameful trustworthy, take words seriously and mean what they say. PreQin Chinese simply believed there was 天 Tian to follow and whoever does against 天 is on the wrongside. Qin didn't unite China but had destroyed others by brute force who were of higher achievement in Arts and other academic fields. Qin had done more damages to the Chinese civilization than introducing benefits or establishing commonwealth. People and officials no longer opened their minds to honest opinions owing to fear of all sorts of brutal penalties and threats. Fear instead of enthusiastic passion took place to dominate the Chinese ever since. The Chinese today therefore are generally found to be less likely to tell of their true feelings and thoughts , and would rather disguise their inner minds to agree with whoever they deem as the authority or of a higher rank. Tian天 no longer had any power to guide the people and instead Emperor and royal members and officials were the main players in roles to be pleased. The postQin Chinese share very similar degree of fear in their livelihood much as the European had during the Dark Age, only that the European had ended their Dark Age but the general Chinese people of now still are very far from being even made aware of.
(My broken English is quite limited in capacity to express everything in full details. I welcome any comments and I hope my ideas can assist those who are learning about China or Chinese culture.)
In general, 天Tian isn't strixtly defined but rather mentioned in Chinese ancient texts. Laozi老子 had used both 天Tian and 道Dao to mean the same interchangebly, so did all other texts, there were always numerous terms to mean the same 天Tian, such as 上帝 ，帝，上天，蒼天，皇天，道，大道，天道，有者，造物者，生生者，乾坤，陰陽，太極，無極，無有& etc.
Some authors of PreQin and PostQin did attempt to define 天 or the equivalents but none have become standard, therefore unlike the Quran or Bible where all the followers refer to the same texts and get taught collectively in mosques and churches regularly, Chinese ideas never have become institutionalised nor standardised, many Chinese simply don't learn and bother. The Chinese today largely are ignorant about anything higher in concepts that arent worldly, they practise their courtesy only when they regard someone is of financial interest to them.
(My eyelids have got swollen by infection, I will rest now and will find my spare hours to post again)
Happy New Year