Thomas De Quincey said this quote

If once a man indulges himself in murder, very soon he comes to think little of robbing; and from robbing he next comes to drinking and Sabbath-breaking, and from that to incivility and procrastination.

~ Thomas De Quincey

But my way of writing is rather to think aloud, and follow my own humours, than much to consider who is listening to me; and, if I stop to consider what is proper to be said to this or that person, I shall soon come to doubt whether any part at all is proper.

~ Thomas De Quincey

Guilt and misery shrink, by a natural instinct, from public notice: they court privacy and solitude: and even in their choice of a grave will sometimes sequester themselves from the general population of the churchyard, as if declining to claim fellowship with the great family of man; thus, in a symbolic language universally understood, seeking (in the affecting language of Mr. Wordsworth)’ Humbly to expressA penitential loneliness.

~ Thomas De Quincey

here was the secret of happiness, about which philosophers had disputed for so many ages, at once discovered; happiness might now be bought for a penny, and carried in the waistcoat-pocket; portable ecstasies might be had corked up in a pint-bottle; and peace of mind could be sent down by the mail.

~ Thomas De Quincey