put on one's thinking cap

Think or reflect seriously, as in A new slogan? I'll have to put on my thinking cap for that. This term originated in the late 1800s and replaced considering cap, which dates from the early 1600s.

Common Names:

Name	Pronounced	Usage
Zaxaria	-	Old Church Slavic
Heidi	HIE-dee (German, English), HAY-dee (Finnish)	German, Swedish, Norwegian, Danish, Finnish, English
Marion	['mɛəriən]
Seneca	SEN-ə-kə (English)	Ancient Roman
Helgi	-	Ancient Scandinavian
Clytia	-	Greek Mythology (Latinized)