With what martial advice did Mr.Bennet provide Elizabeth? Is his advice soundly?

Mr. Bennet says he knows that Elizabeth could never be happy unless she really liked Darcy and is not just marying him for money and family reputation,

"But let me advise you to think better of it. I know your disposition, Lizzy. I know that you could be neither happy nor respectable, unless you truly esteemed your husband; unless you looked up to him as a superior. Your lively talents would place you in the greatest danger in an unequal marriage. You could scarcely escape discredit and misery. My child, let me not have the grief of seeing you unable to respect your partner in life. You know not what you are about."