What was Jose Rizal's opinion on the need for a national language?

In his second novel, El Filibusterismo, Rizal made Basilio say:

"On the contrary, if the knowledge of Castilian may bind us to the government, in exchange it may also unite the islands among themselves."

Simoun countered:

"A gross error! You are letting yourselves be deceived by big words and never go to the bottom of things to examine the results in their final analysis. Spanish will never be the general language of the country, the people will never talk it, because the conceptions of their brains and the feelings of their hearts cannot be expressed in that language--each people has its own tongue, as it has its own way of thinking!"

Here Basilio believes that Castillian, a foreign tongue, will unite the country. Note, however, that Simoun's reply does not refute Basilio's stand that Castillian will unite the country. Instead Simoun says that "Spanish will never be the general language of the country" because "each people has its own tongue, as it has its own way of thinking".

Thus, if we base our interpretation on what Rizal's characters were saying, we can conclude that Rizal has the following opinion about the need for a national language:

a. A foreign language can unite the country.

b. But it will be very difficult, if not impossible, to propagate the use of the language throughout the country.

Rizal, therefore, is ambivalent on the issue of a national language. Even his "Ang hindi marunong magmahal sa sariling wika", although frequently cited by rabid supporters of the existing Philippine national language policy, does not really say anything about the utility of a national language. All it says is the need for a person to learn his native tongue, which fits perfectly with the nativist tendencies of Jose Rizal.