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Prolog: a (b, c) and a (X, Y): - a (Y, X), the request a (c, b) returns an infinite true?

Here is my knowledge base:

a(b,c). 
a(X,Y):-a(Y,X).

Here is my request: a(c,b).

I am using SWI-Prolog. I thought this request would print the program "true". However, instead it prints "true" and continues to print true if I hit the semicolon ... before FOREVER.

Why doesn't he stop?

My thoughts: firstly, X is associated with b and Y is associated with c. Prolog then checks a (b, c) and finds that it is true. Therefore, a (c, b) is also true, and SWI-Prolog should print true once. However, since it prints the truth forever, while I continue to hit this semicolon, it makes me think that something recursive is happening. Where is this going? Help!

EDIT: More specifically, my question is why does the program pause after each “true” and wait for me to press the semicolon or another key, and not just do it? If I have two predicates of a person (socrates) and a mortal (X): - people (X), the answer to the query mortal (socrates) will be a single "true". (Sorry if I couldn’t make it clear above.)

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a(c,b) , . a(c,b) , . .. Prolog - , .. , , .

, , , ,

a_fact(b, c).
a(X, Y) :- a_fact(X, Y).
a(Y, X) :- a_fact(X, Y).

... . , SWI-Prolog .

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