to open, to begin, to explain, to inform, letter
諬 centers on initiating communication: opening a topic, beginning to explain, informing someone, or sending a letter. The meanings share the idea of starting a communicative act.
諬 combines 言 (speech) with a phonetic component that resembles 尤 over 禾. The exact historical development is uncertain, but it likely follows a phono-semantic pattern where the upper part contributed the sound and 言 indicates verbal communication.
The bottom 言 (speech) supports a shape that looks like a person 尤 standing beside a grain plant 禾. Imagine someone beginning to speak, opening a conversation to explain the harvest, or writing a letter about it.
For ケイ, picture a letter being opened with a paper knife: the 'K' of knife and the long 'A' sound together suggest ケイ, as you begin to read the message.