What is an object of the verb 'De' for the use of 'Ce dont'?

Question

The object of a preposition would be like this:

Avec quoi écris-tu ?
(What do you write with?)

With quoi being the object of the preposition avec (with); however when you use the preposition de you must use Ce Dont instead of quoi.

In this example:

C'est ce dont je me souviens.
(That's what I remember)

You never see the preposition de, anywhere in the clause. How is it an object of a preposition, which is not even present in the sentence? Whereas in the first example you see the preposition avec in the sentence.

Please explain!

Answer 1

Dont means de qui (for people), duquel / de laquelle / desquels / desquelles (for identified things) or de quoi (for unidentified things). Depending on the context, you may have the choice of what to use, or one may be mandatory. The two most important aspects of those rules is that:

• when asking a question, it is never dont (thus, de quoi te souviens-tu?, not Dont te souviens-tu?)

• after ce, it is always dont (thus, c'est ce dont je me souviens, not C'est de quoi je me souviens)

See this question for more details.