two pronunciations: ðə before a consonant, and ði before a vowel.
The sound ð is often deictic. That means it points to something in the world (or something that's been pointed out earlier in the course of discussion). (digit - doigt - deixis)
e.g. there, them, they, then, this, that, thus, therefore, these, those, thither, whither, etc.
- The more, the merrier...
- The longer I waited to go to the hospital, the worse it got...