The French expression Cela va sans dire (the literal translation of this goes without saying) has become very familiar to the English speaking world. The idiom means there is no need to say it, it’s obvious, it’s evident... but I’m saying it anyway.
We can also say Ça va sans dire which has exactly the same meaning. Ça and cela are both demonstrative pronouns.
During the Congress of Vienna, which was held at the Schönbrunn Palace, from November 1814 to June 1815, the Prussian chancellor was defending his own interests in the European reorganisation following the defeat of Napoleon, and pronounced an overconfident,"Cela va sans dire!".
Charles-Maurice de Talleyrand-Périgord, French prince, politician and diplomat, promptly replied : “Si cela va sans dire, ça ira encore mieux en le disant.” A word pun meaning: if this goes without saying, it will go even better saying it.
If you want to show off your French, go ahead then: pronounce either ça va sans dire o cela va sans dire as long as you pronounce these expressions correctly.