a. 无前因的, 非创造的, 自存的

[ adj ]
having no cause or apparent cause
<adj.all>
a causeless miraclefortuitous encounters--strange accidents of fortune
we cannot regard artistic invention as...uncaused and unrelated to the times

Uncaused \Un*caused"\, a.
Having no antecedent cause; uncreated; self-existent;
eternal. --A. Baxter.