There is within you a place where you live. When you rest there sincerely, honestly, and openly, you are clean. You have wisdom. This is called innocence.
It is most vulnerable. Usually you keep it hidden from the world. You show it only when you choose to. When you do show it, you often cloak it in one manner or another. Perhaps you couch it in humor. Maybe defend it with anger or sarcasm. Maybe hide it with denial. Maybe mask it with niceties.
How you hold that within determines the nature of your inner thoughts. That is the attitude and relationship you hold with the world. That colors your being. That, more than anything else, determines the nature of your karma. That is what Swami Vivikenanda is referring to here:
We are what our thoughts have made us; so take care about what you think.
Words are secondary. Thoughts live; they travel far. – Swami Vivikenanda